Consulta: subjectFacets:"Competition"
Registros recuperados: 214
Data/hora: 12/06/2024 08:53:24

Análisis de la red de valor del mango Ataulfo en la subcuenca del Río Atoyac, estado de Guerrero.
Provedor de dados: 32
Autores: Embris Jiménez, Omar.
El presente trabajo tuvo como objetivo definir las causas que existen en torno al problema de la red de valor del mango Ataulfo en la subcuenca de Atoyac, así como identificar las alternativas de aprovechamiento de las ventajas competitivas propias del territorio y del potencial productivo que permitan generar ingresos a la población. Aunque el mango Ataulfo es líder en rendimiento y representa los mayores ingresos para los productores, presenta bajo nivel competitivo, debido a: altos costos de producción y postcosecha, baja calidad del producto, deficiente organización, escasez de capital de trabajo, escasez de asistencia técnica y capacitación, y poco vínculo entre los agentes: productor, empacador y cliente. Para revertir este fenómeno, es necesario que...
Palavras-chave: Comercialización; Competitividad; Mango ataulfo; Red de valor; Ataulfo mango; Competition; Marketing; Value network; EDAR; Desarrollo Sostenible de Zonas Indígenas; Maestría Tecnológica.
Ano: 2011
URL: http://hdl.handle.net/10521/654

Efecto del depredador cryptolaemus montrouzieri (Coleoptera: Coccinellidae) en la actividad parasítica de anagyrus kamali (Hymenoptera: Encyrtidae) sobre cochinilla rosada del hibisco.
Provedor de dados: 32
Autores: Hernández Moreno, Salvador.
En varios países se han introducido Anagyrus kamali y Cryptolaemus montrouzieri para el control de la cochinilla rosada del hibisco (CRH) Maconellicoccus hirsutus, pero no se han establecido las interacciones entre estos enemigos naturales. En el presente trabajo se evaluó la interacción de C. montrouzieri (larvas de cuarto ínstar y hembras adultas) y la actividad parasítica de A. kamali sobre CRH en condiciones de laboratorio. Para determinar la interferencia entre el depredador y el parasitoide se realizaron pruebas de liberación individual y simultánea de ambas especies mediante pruebas de elección y no elección, utilizando como huésped/presa ninfas de tercer ínstar de CRH no parasitadas y parasitadas por A. kamali. Las ninfas parasitadas tenían...
Palavras-chave: Maconellicoccus hirsutus; Control biológico; Enemigos naturales; Competencia; Biological control; Natural enemies; Competition; Maestría; Entomología y Acarología.
Ano: 2011
URL: http://hdl.handle.net/10521/594

Concomitant Patterns in Avian and Mammalian Body Length Changes in Denmark
Provedor de dados: 7
Autores: Schmidt, Niels Martin; Royal Veterinary and Agricultural University; nms@kvl.dk; Jensen, Per Moestrup; Royal Veterinary and Agricultural University; pmj@kvl.dk.
We gathered length data on 61 Danish breeding birds from the past 200 years, and related the pattern of change to present body mass and other ecological parameters. Body mass was the only parameter significantly correlated with the rate of change, and the emerging pattern in the rate of change followed the island rule. That is, smaller species have become larger and vice versa, while the medium-sized species remain essentially unchanged. The suggested optimal body mass was around 85 g. Though orders of magnitude lower, the pattern in avian body size change was similar to that of Danish mammals. Our analyses suggest that increasing habitat fragmentation leads to altered body size towards being medium-sized in Danish vertebrates. The changing landscape,...
Tipo: Peer-Reviewed Reports
Palavras-chave: Body length; Habitat fragmentation; Island biogeography; Island rule; Aves; Reproductive output; Migration; Feeding category; Competition; Avoidance; Tolerance.
Ano: 2005

Linking Keystone Species and Functional Groups: A New Operational Definition of the Keystone Species Concept
Provedor de dados: 7
Autores: Davic, Robert D; Ohio Environmental Protection Agency; r_davic@yahoo.com.
The concept of the "keystone species" is redefined to allow for the a priori prediction of these species within ecosystems. A keystone species is held to be a strongly interacting species whose top-down effect on species diversity and competition is large relative to its biomass dominance within a functional group. This operational definition links the community importance of keystone species to a specific ecosystem process, e.g., the regulation of species diversity, within functional groups at lower trophic levels that are structured by competition for a limited resource. The a priori prediction of keystone species has applied value for the conservation of natural areas.
Tipo: Peer-Reviewed Reports
Palavras-chave: Keystone species; Competition; Dominance; Feeding guilds; Functional groups; Power laws; Species diversity; Biomass dominance.
Ano: 2003

JUVENILE HEIGHT GROWTH RATES AND SORTING OF THREE NOTHOFAGUS SPECIES ON AN ALTITUDINAL GRADIENT
Provedor de dados: 73
Autores: Cárdenas Garrido,Cecilia; Lusk,Christopher H.
It has been argued that if the cost of investment in cold resistance mechanisms detracts significantly from growth rates, then height growth tradeoffs should control species sorting on latitudinal temperature gradients. Applying the same logic to altitudinal temperature gradients, it can be predicted that species' upper altitudinal limits will be fixed by their degree of cold resistance, whereas the lower altitudinal limits of species growing higher up will be set by competition from faster-growing thermophilous species. We tested this prediction for three Nothofagus species on an altitudinal gradient (1,100 - 1,700 m) near Termas de Chillán, on the lower western slopes of the Andean Cordillera. We used retrospective methods to measure height increment...
Tipo: Journal article
Palavras-chave: Altitude; Cold resistence; Competition; Temperate forest; Tradeoff.
Ano: 2002
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432002000100004

Characteristics of muskmelon fruits in relation to temporary row cover and the number of fruits
Provedor de dados: 75
Autores: Pereira,Auderlan M; Queiroga,Roberto CF; Pereira,Francisco Hevilásio F; Silva,Zaqueu L; Santos,Everaldo F.
ABSTRACT The muskmelon plants allow several ways to manipulate sources/drains ratio. The objective of this work was to evaluate characteristics of the productivity and quality of Cantaloupe melon fruits due to the temporary use of row cover and the number of fruits per plant. The experiment was carried out from August to December 2014, at Universidade Federal de Campina Grande (UFCG), Paraiba State, Brazil. The experimental design was randomized blocks with treatments allocated in split plots 5x3, with four replicates. The authors reported permanence time of the row cover at different times in the plot {20, 24, 28, 32, and 36 days after transplanting (DAT)} and, in the subplots, the number of fruits per plant (plants with one fruit, plants with two fruits...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Cucumis melo; Competition; Physiology and yield.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-05362017000400591

Воздействие глобальных климатических и региональных  факторов на мелких пелагических рыб Чёрного  моря.
Provedor de dados: 13
Autores: Шульман, Г. Е.; Никольский, В. Н.; Юнева, Т. В.; Щепкина, А. М.; Бат, Л.; Кидейш, А. Е.
Рассмотрена многолетняя динамика содержания жира у шпрота и анчоуса Чёрного моря как индикаторов обеспеченности пищей в связи с температурой воды, концентрацией фитопланктона, величинами запасов и уловов этих рыб. Глобальным климатическим фактором, оказывающим прямое и косвенное влияние на обеспеченность мелких пелагических рыб Чёрного моря пищей, является температура. Региональные факторы, воздействующие на состояние шпрота и анчоуса, – пищевая конкуренция, речной сток и загрязнение водной среды.
Tipo: Journal Contribution
Palavras-chave: Шпрот; Анчоус; Содержание жира; Обеспеченность пищей; Температура; Конкуренция; Фитопланктон; Запасы и уловы; Чёрное море; Sprat; Anchovy; Fat content; Food supply; Temperature; Competition; Phytoplankton; Stocks and yields; Black Sea; Камса; Вміст жиру; Забезпеченість їжею; Конкуренція; Фітопланктон; Вилови; Чорне море.
Ano: 2007
URL: http://repository.ibss.org.ua/dspace/handle/99011/854

Daily variation of zooplankton abundance and evenness in the Rosana reservoir, Brazil: biotic and abiotic inferences
Provedor de dados: 76
Autores: Takahashi,Érica M.; Lansac-Tôha,Fábio A.; Dias,Juliana D.; Bonecker,Claudia C.
The zooplankton community presents stochastic temporal fluctuation and heterogeneous spatial variation determined by the relationships among the organisms and environmental conditions. We predicted that the temporal and spatial zooplankton distribution is heterogeneous and discrete, respectively, and that the daily variation of most abundant species is related to environmental conditions, specifically the availability of resources. Zooplankton samples were collected daily at three sampling stations in a lateral arm of the Rosana Reservoir (SP/PR). The zooplankton did not present significant differences in abundance and evenness among sampling stations, but the temporal variation of these attributes was significant. Abiotic variables and algal resource...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Temporal variation; Rotifers; Microcrustaceans; Coexistence; Competition.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212014000100003

The aggregation of Chauliognathus species (Coleoptera, Cantharidae) and its possible role for coexistence and mimicry
Provedor de dados: 76
Autores: Machado,Vilmar; Araújo,Aldo Mellender de.
The relative population sizes of a species complex of Chauliognathus are reported, as well as their spatial distribution associated with different patches of food plants. Field work was done at Fazenda Santa Isabel, municipality of Guaíba, State of Rio Grande do Sul, Brazil. The results suggest that two mechanisms account for the reduction in food competition among the species involved: one is asynchrony in the appearance of the species in the area, and the other is aggregation in different patches of food plants. Since the species here reported show a similar colour pattern (yellow-black) the possibility of the occurrence of serial mimicry in this complex of species is dicussed.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Chauliognathus; Aggregation; Competition; Mimicry; Coleoptera.
Ano: 2001
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212001000200002

Competicao de herbicidas na cotonicultura herbacea.
Provedor de dados: 14
Autores: BELTRÃO, N. E. de M.
bitstream/item/65801/1/Competicao-de-herbicidas.pdf
Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E)
Palavras-chave: Competicao; Oxidazon; Gossypium hirsutum L; Annual cotton; Herbicide; Competition; Perennial cotton.; Algodão Herbáceo; Herbicida.; Alachlor; Diuron; Fluometuron; Trifluralin.
Ano: 1976
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/262415

Competição agroflorestal de erva-mate: qual o sistema mais rentavel?
Provedor de dados: 14
Autores: DOSSA, D.
bitstream/CNPF-2009-09/15749/1/com_tec44.pdf
Tipo: Comunicado Técnico (INFOTECA-E)
Palavras-chave: Sistema agroflorestal; Competição; Agroforestry systems; Competition; Erva mate; Espécie nativa; Manejo; Integração.
Ano: 2000
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/289937

Competição de cultivares de arroz (oryza sativa L.) de sequeiro e irrigado para o Mato Grosso do Sul.
Provedor de dados: 14
Autores: HECKLER, J. C.; SOUSA, P. G. de; VALARINI, P. J.
bitstream/item/66144/1/CPAO-PESQ.-AND.-7-80.pdf
Tipo: Outras publicações técnicas (INFOTECA-E)
Palavras-chave: Sequeiro; Irrigado; Cultivar; Mato Grosso do Sul; Competition; Brasil.; Arroz; Competição de Variedade; Cerrado; Oryza Sativa.; Rice; Varieties.
Ano: 1980
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/234720

Estudo de populacao de plantas em consorcio.III. Mamona/Sorgo.
Provedor de dados: 14
Autores: AZEVEDO, D. M. P. de; BATISTA, F. A. S.; LIMA, E. F.; NOBREGA, L. B. da; VIEIRA, D. J.
bitstream/item/33309/1/CNPA-DOCUMENTOS-37-ESTUDO-DE-POPULACAO-DE-PLANTAS-EM-CONSORCIO-III-MAMONA-SORGO-FL-02961.pdf
Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)
Palavras-chave: Consorcio de planta; Competicao de planta; Sorghm bicolor; Brasil; Paraiba; Monteiro; Castor-bean; Sorghum Intercropping; Competition; Cropping system.; Mamona; Ricinus Communis; Sorgo.
Ano: 1999
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/271628

Controle integrado de plantas daninhas em agroecossistemas cotonicolas.
Provedor de dados: 14
Autores: BELTRAO, N. E. de M.; AZEVEDO, D. M. P. de; NOBREGA, L. B. da; VEIRA, D. J.
bitstream/item/33329/1/CONTOLE-INTEGRADO.pdf
Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)
Palavras-chave: Herbáceo; Controle; Consorciação; Competição; Caupi; Brasil; Gurinhem; Ceara; Iguatu; Annual cotton; Bean; Competition; Cultural; Practices; Herbicide; Yield.; Algodão; Erva Daninha; Herbicida; Gossypium Hirsutum; Manejo; Rendimento; Vigna Unguiculata.; Sousa; Intercropping; Weed control.
Ano: 1992
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/263420

Ensaio de espécies florestais no planalto do Tapajós.
Provedor de dados: 14
Autores: YARED, J. A. G.; CARPANEZZI, A. A.; CARVALHO FILHO, A. P.
bitstream/item/28829/1/CPATU-BP11.pdf
Tipo: Séries anteriores (INFOTECA-E)
Palavras-chave: Competicao; Floresta Nacional do Tapajos; Pará; Brasil; Specie; Competition; Forest; Growth.; Altura; Crescimento; Diâmetro; Espécie; Floresta; Silvicultura.; Amazonia; Height; Diameter; Silviculture.
Ano: 1980
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/376821

Aspectos da competicao entre plantas com especial atencao ao algodoeiro-Gossypium hirsutum L.
Provedor de dados: 14
Autores: BELTRÃO, N. E. de M.
A competicao e suas modalidades; Informes da pesquisa sobre competicao na cultura algodoeira no centro-sul do Brasil e no mundo; Informes da pesquisa sobre competicao na cultura algodoeira no nordeste brasileiro.
Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E)
Palavras-chave: Arboreo; Competicao; Gossypium hirsutum L; Brasil; Nordeste; Weed; Competition; Perennial cotton; Annual cotton.; Algodão Herbáceo; Erva Daninha.
Ano: 1977
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/262412

When everything is not everywhere but species evolve: an alternative method to model adaptive properties of marine ecosystems
Provedor de dados: 5
Autores: Sauterey, Boris; Ward, Ben A.; Follows, Michael J.; Bowler, Chris; Claessen, David.
The functional and taxonomic biogeography of marine microbial systems reflects the current state of an evolving system. Current models of marine microbial systems and biogeochemical cycles do not reflect this fundamental organizing principle. Here, we investigate the evolutionary adaptive potential of marine microbial systems under environmental change and introduce explicit Darwinian adaptation into an ocean modelling framework, simulating evolving phytoplankton communities in space and time. To this end, we adopt tools from adaptive dynamics theory, evaluating the fitness of invading mutants over annual timescales, replacing the resident if a fitter mutant arises. Using the evolutionary framework, we examine how community assembly, specifically the...
Tipo: Text
Palavras-chave: Phytoplankton; Competition; Trait-based adaptive strategies; Adaptive dynamics; Eco-evolutionary dynamics; Trade-off; Community; Global circulation model.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00617/72883/71917.pdf

Resource Competition Affects Plankton Community Structure; Evidence from Trait-Based Modeling
Provedor de dados: 5
Autores: Sourisseau, Marc; Le Guennec, Valerie; Le Gland, Guillaume; Plus, Martin; Chapelle, Annie.
Understanding the phenology of phytoplankton species is still a challenge and despite a lot of theoretical work on competition for ressources this process is under-represented in deterministic models. To study the main driver of the species selection, we thus used a trait-based model that keeps phenotypic variability through physiological trait parameterization. We next validate the results by using a key species, the toxic dinoflagellate Alexandrium minutum. Due to their monitoring, we show that harmful algae are ideal models for studying ecological niches and for contributing to this more global challenge. As a first step, a dimensionless model of an estuary (France) was built with water temperature and water exchanges deduced from a hydro-dynamic model....
Tipo: Text
Palavras-chave: Droop; Competition; Inter-specific; Estuary; Bay of Brest; Alexandrium minutum; Phenology; Niches.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00373/48414/48624.pdf

Competition for food reduces disease susceptibility in a marine invertebrate
Provedor de dados: 5
Autores: Pernet, Fabrice; Lugue, Klervi; Petton, Bruno.
Competition between organisms interfere in host and pathogen dynamics in ways that are difficult to predict. By one side, competitors can reduce the food supply and cause nutritional stress. Such stress could further modulate the susceptibility to infection by altering immune response or metabolic rate of the host. Alternatively, competitors may trap pathogens before they reach the focal host, and therefore reduce, enhance, or have no effect on infection according to the competitor's susceptibility to the infection. To better understand how competition influences host and pathogen interactions, we experimentally assessed the relative importance of competition for pathogens and resources on the severity of a viral disease infecting the Pacific oyster...
Tipo: Text
Palavras-chave: Competition; Crassostrea gigas; Disease ecology; Filtration; Ostreid herpesvirus 1; Pathogen.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00692/80375/83493.pdf

Response to domestication and selection for growth in the European sea bass (Dicentrarchus labrax) in separate and mixed tanks
Provedor de dados: 5
Autores: Vandeputte, Marc; Dupont Nivet, M; Haffray, P; Chavanne, H; Cenadelli, S; Parati, K; Vidal, Marie-odile; Vergnet, Alain; Chatain, Beatrice.
Selective breeding of European sea bass (Dicentrarchus labrax) receives a growing interest, as the estimated heritability of growth is medium to high. In this study, we compared the offspring of four groups of sea bass sires, mated with the same wild dams: wild (W), first generation of domestication (D), first generation of mass selection for length (M), first generation of PROSPER-like selection for length (P). The comparison was done both in replicated tanks (separate rearing) and in mixed tanks (mixed rearing) where sire origins were recovered by genotyping of eight microsatellite markers. Weight, length and growth rate were measured from day 238 post-fertilization (69 g mean weight) to day 611 post-fertilization (390 g mean weight). Both in mixed and...
Tipo: Text
Palavras-chave: Nephrocalcinosis; Competition; Microsatellites; Parentage assignment; Realized heritability; Selection response; Growth; Selective breeding; Dicentrarchus labrax; European sea bass.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-5303.pdf

Modelling benthic invasion by the colonial gastropod Crepidula fornicata and its competition with the bivalve Pecten maximus . 1. A new 0D model for population dynamics of colony-forming species
Provedor de dados: 5
Autores: Menesguen, Alain; Gregoris, Thomas.
The north-American marine gastropod Crepidula fornicata (Linné 1758), commonly called slipper limpet, has been introduced accidentally in Great Britain, along with American oysters (Crassostrea virginica) at the end of the 19th century. Its spreading, enhanced by oyster transport and international shipping, turned into invasion of a lot of benthic grounds along the North-European coasts. When local conditions are favorable to larval confinement and adult growth, the invasion by very dense populations may deeply change initially sandy or muddy benthic communities into similar “slipper limpet communities”. Competition for space eliminates several species of native infauna, and hampers the survival of some epibenthic bivalves such as the scallop Pecten...
Tipo: Text
Palavras-chave: Crepidula fornicata; Invasive species; Benthic gastropod; Colony model; Matching matrix; Pecten maximus; Competition; Population dynamics; Limit cycle.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00415/52601/53491.pdf

Short-term interactions between phytoplankton and intertidal seagrass vegetation in a coastal lagoon (Bassin d'Arcachon, SW France)
Provedor de dados: 5
Autores: De Wit, Rutger; Troussellier, Marc; Courties, Claude; Buffan-dubau, Evelyne; Lemaire, Emmanuelle.
We experimentally simulated the temporality of the interactions between intertidal seagrasses and phytoplankton in the context of nutrient enrichment from continental origin. Phytoplankton development was retarded after 1-day exposure to intertidal Zostera noltii Hornemann vegetation samples, with respect to control treatments. This was not explained by resource competition and we hypothesized a direct interference between seagrass leaves and phytoplankton. After separation from the vegetation in 5-day incubations, the final yield of large phytoplankton, mainly diatoms and haptophytes, was determined by nutrient loading. In contrast, Synechococcus-like cells (SYN), phototrophic picoeukaryotes and nanophytoplankton decreased after day 3, most likely due to...
Tipo: Text
Palavras-chave: Competition; Allelopathy; Zostera noltii; Sediment; Intertidal vegetation; Flow cytometry; Photosynthetic pigments.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00106/21717/19414.pdf

Environmental controlling factors of copepod communities in the Gulf of Tunis (south western Mediterranean Sea)
Provedor de dados: 5
Autores: Ben Lamine, Yosra; Pringault, Olivier; Aissi, Mehdi; Ensibi, Cherif; Mahmoudi, Ezzeddine; Kefi, Ons Daly Yahia; Yahia, Mohamed Nejib Daly.
The copepod community structure and the distribution of the main groups of zooplankton were studied along an inshore-offshore gradient in the Gulf of Tunis during the rainy and dry seasons of 2007-2008. Hydrological parameters were also measured to assess the potential role of abiotic and biotic factors in the distribution of copepod species. The copepod community in the Gulf of Tunis comprises 86 species dominated by Paracalanus parvus, Clausocalanus lividus, Centropages kroyeri and Acartia clausi. Time had a greater influence than space (horizontal and vertical gradients) in shaping the copepod community structure with a significant influence of the seasons; winter (cold and rainy) resulted in hydrological conditions that were strongly different from...
Tipo: Text
Palavras-chave: Copepod diversity; Multivariate analysis; Temperature; Salinity; Top-down control; Competition.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00275/38670/73416.pdf

Small-scale spatial and temporal interactions among benthic crustaceans and one fish species in the Bay of Biscay
Provedor de dados: 5
Autores: Trenkel, Verena; Le Loch, Francois; Rochet, Marie-joelle.
In the summer of 2004, a video survey was carried out in the northern part of the central mud bank (Grande Vasiere) of the Bay of Biscay to study the small scale relationship between the dominant crustacean megafauna Nephrops norvegicus, Munida rugosa and Goneplax rhomboides and juvenile hake (Merluccius merluccius). Using a towed body, high-resolution videos were recorded in six sampling sites. Statistical modelling using generalised additive models (GAM) revealed variations in activity patterns for two species. More N. norvegicus were observed outside their burrows at dawn and somewhat at dusk (no observations during night) while G. rhomboides was less observed in the morning. In addition, reduced spatial overlap between G. rhomboides and N. norvegicus...
Tipo: Text
Palavras-chave: Competition; Variations in activity patterns; Video; Benthos.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2614.pdf

Can Fishing Pressure Invert the Outcome of Interspecific Competition? The Case of the Thiof and of the Octopus Along the Senegalese Coast
Provedor de dados: 5
Autores: Nguyen-phuong, Thuy; Nguyen-ngoc, Doanh; Auger, Pierre; Ly, Sidy; Jouffre, Didier.
We present a mathematical model of two competing marine species that are harvested. We consider three models according to different levels of complexity, without and with species refuge and density-independent and density-dependent species movement between fishing area and refuge. We particularly study the effects of the fishing pressure on the outcome of the competition. We focus on conditions that allow an inferior competitor to invade as a result of fishing pressure. The model is discussed in relationship to the case of the thiof and the octopus along the Atlantic West African coast. At the origin, the thiof was abundant and the octopus scarce in that region. Since, the fishing pressure has strongly increased in some fishing areas leading to the...
Tipo: Text
Palavras-chave: Competition; Refuge; Density-dependent migration; Density-independent migration; Fishing pressure.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00625/73744/74499.pdf

Des îles et des épiciers. S’approvisionner en biens alimentaires dans les îles du Ponan
Provedor de dados: 5
Autores: Guingot, Marie.
The Ponant Islands are diverse in terms of population, surface or distance from the continent. Most of food products consumed on these islands are coming from the continent. It is therefore necessary to transport them to the island, all along a route whose main element is the sea crossing. This is what makes island supply special. Grocery stores are not equivalent in all Ponant Islands. The island maritime service requires the local grocers to adapt and implement supply strategies. This results in different modes of conveyance for food products to island territories. While most of the food products consumed on these islands are bought in local grocery stores, consumers are increasingly reaching out to continental grocery stores. This is creating new flows...
Tipo: Text
Palavras-chave: Epicerie; Desserte maritime insulaire; Approvisionnement; Acheminement des marchandises; Concurrence; Îles du Ponant; Commerce de détail; Consommateur.; Grocery store; Island maritime service; Supply; Flow of goods; Competition; Ponant Islands; Retail trade; Consumer.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00637/74885/75283.pdf

Disentangling ecosystem engineering from short-term biotic effects of a strong invader on a native foundation species
Provedor de dados: 5
Autores: Proença, Barbara; Romuald, Marine; Auby, Isabelle; Ganthy, Florian; Sottolichio, Aldo; Michalet, Richard.
Ecosystem engineering effects of dominant species on habitats and consequently on other species are likely to propagate through time at longer distance than the close neighbourhood. Such effects are important to disentangle from short-term biotic effects, especially in biological invasions, as engineering can explain changes in invasion rates over the course of the invasion. We assessed the contribution and spatial dynamics of ecosystem engineering effects of a strong invader, the cordgrass Spartina anglica, on Zostera noltei, a foundation seagrass species of muddy intertidal systems in Europe. Z. noltei transplants were grown at different positions along transects crossing intact S. anglica patches, cut patches and nearby bare sediment on tidal flats in...
Tipo: Text
Palavras-chave: Biological invasion; Competition; Ecosystem engineer; Spartina anglica; Zostera noltei.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00507/61875/67507.pdf

Données économiques maritimes françaises 2016
Provedor de dados: 5
Autores: Kalaydjian, Regis; Girard, Sophie.
The "French Maritime Economic Data" report is periodically published by Ifremer since 1997. It presents an economic assessment of the French maritime activities, their position in the national economy and in the world competition, as well as the significance of non market public services. Maritime activities in the industrial sector are assessed using a standard metrics to facilitate the periodical update of the report: turnover, gross value added, employment, number of enterprises, exports. These indicators are expressed at national level. The public sector is described by annual budgets, number of staff and personnel costs, broken down into the different public policy functions. Regional indicators are provided on activities whenever relevant and...
Tipo: Text
Palavras-chave: Economie; Concurrence; Croissance; Emploi; Environnement; Europe; France; Industrie; Marin; Maritime; Valeur ajoutée; Secteur public; Services.; Economy; Competition; Employment; Environment; Europe; France; Growth; Industry; Marine; Maritime; Public sector; Value added; Services.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00388/49962/50614.pdf

High-Throughput Identification of Candidate Strains for Biopreservation by Using Bioluminescent Listeria monocytogenes
Provedor de dados: 5
Autores: El Kheir, Sara M.; Cherrat, Lamia; Awussi, Ahoefa A.; Ramia, Nancy E.; Taha, Samir; Rahman, Abdur; Passerini, Delphine; Leroi, Francoise; Petit, Jeremy; Mangavel, Cecile; Revol-junelles, Anne-marie; Borges, Frederic.
This article describes a method for high-throughput competition assays using a bioluminescent strain of L. monocytogenes. This method is based on the use of the luminescent indicator strain L. monocytogenes EGDelux. The luminescence of this strain is correlated to growth, which make it suitable to monitor the growth of L. monocytogenes in mixed cultures. To this aim, luminescence kinetics were converted into a single numerical value, called the Luminescence Disturbance Indicator (LDI), which takes into account growth inhibition phenomena resulting in latency increase, decrease in the luminescence rate, or reduction of the maximum luminescence. The LDI allows to automatically and simultaneously handle multiple competition assays which are required for...
Tipo: Text
Palavras-chave: Biopreservation; Listeria monocytogenes; High-throughput screening assays; Bioluminescence; Competition; Mixed culture; Bioprotection; Antibacterial activities.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00454/56534/58236.pdf

Coastal phytoplankton community dynamics and coexistence driven by intragroup density-dependence, light and hydrodynamics
Provedor de dados: 5
Autores: Barraquand, F.; Picoche, C.; Maurer, Daniele; Carassou, L.; Auby, Isabelle.
Phytoplanktonic communities maintain a high diversity in a seemingly homogeneous environment, competing for the same set of resources. Many theories have been proposed to explain this coexistence despite likely competition, such as contrasted responses to temporal environmental variation. However, theory has developed at a faster pace than empirical evaluation using field data, which requires inferring drivers of community dynamics from observational time series. Here, we combine autoregressive models with a data set spanning more than 20 years of phytoplankton counts every two weeks, together with nutrients and physical variables. By comparing models dominated by nutrients or physical variables (hydrodynamics and climate), we first explore which abiotic...
Tipo: Text
Palavras-chave: Competition; Diatoms; Dinoflagellates; Hydrodynamics; Interactions; MAR; Mutualism; Network; Population dynamics; Seasonality; Time series.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00461/57257/59285.pdf

Phytoplankton competition and coexistence: Intrinsic ecosystem dynamics and impact of vertical mixing
Provedor de dados: 5
Autores: Perruche, Coralie; Riviere, Pascal; Pondaven, Philippe; Carton, Xavier.
This paper aims at studying analytically the functioning of a very simple ecosystem model with two phytoplankton species. First, using the dynamical system theory, we determine its nonlinear equilibria, their stability and characteristic timescales with a focus on phytoplankton competition. Particular attention is paid to the model sensitivity to parameter change. Then, the influence of vertical mixing and sinking of detritus on the vertically-distributed ecosystem model is investigated. The analytical results reveal a high diversity of ecosystem structures with fixed points and limit cycles that are mainly sensitive to variations of light intensity and total amount of nitrogen matter. The sensitivity to other parameters such as remineralisation, growth...
Tipo: Text
Palavras-chave: Water mixing; Dynamical system; Phytoplankton; Competition; Ecosystem; Modelling.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2009/publication-7334.pdf

North Sea saithe Pollachius virens growth in relation to food availability, density dependence and temperature
Provedor de dados: 5
Autores: Cormon, Xochitl; Ernande, Bruno; Kempf, Alexander; Vermard, Youen; Marchal, Paul.
North Sea saithe Pollachius virens, a major top predator in the area, supports the fishery economy of several European countries. However, recent stock assessments suggested a decrease in spawning stock biomass along with a decline in saithe mean weight-at-ages. In this context, we investigated North Sea saithe growth characteristics at the population level. First, saithe annual weight increments and age-length relationships were studied. Modelling of saithe age-length relationships was carried out using (1) the traditional von Bertalanffy growth function model, (2) the Verhulst logistic model and (3) an empirical linear model. Second, the effects of environmental factors on saithe growth were investigated. Explanatory environmental factors included food...
Tipo: Text
Palavras-chave: Bottom-up processes; Von Bertalanffy growth function; Logistic growth; Norway pout; Prey availability effects; Density-dependence; Predator-prey interactions; Resource limitation; Competition.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00314/42499/41875.pdf

Spatial interactions between saithe (Pollachius virens) and hake (Merluccius merluccius) in the North Sea
Provedor de dados: 5
Autores: Cormon, Xochitl; Loots, Christophe; Vaz, Sandrine; Vermard, Youen; Marchal, Paul.
Spatial interactions between saithe (Pollachius virens) and hake (Merluccius merluccius) were investigated in the North Sea. Saithe is a well-established species in the North Sea, while occurrence of the less common hake has recently increased in the area. Spatial dynamics of these two species and their potential spatial interactions were explored using binomial generalized linear models (GLM) applied to the International Bottom Trawl Survey (IBTS) data from 1991 to 2012. Models included different types of variables: (i) abiotic variables including sediment types, temperature, and bathymetry; (ii) biotic variables including potential competitors and potential preys presence; and (iii) spatial variables. The models were reduced and used to predict and map...
Tipo: Text
Palavras-chave: Biotic interactions; Competition; Generalized linear models; Hake; North Sea; Overlap; Predator-prey relationship; Saithe; Species distribution modelling.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00200/31146/29847.pdf

Horizontal distribution and overlap of planktivorous fish stocks in the Norwegian Sea during summers 1995–2006
Provedor de dados: 5
Autores: Rong Utne, Kjell; Huse, Geir; Ottersen, Geir; Holst, Jens C.; Zabavnikov, Vladimir; Jacobsen, Jan A.; Óskarsson, Guđmundur J.; Nøttestad, Leif.
The Norwegian Sea harbours several large pelagic fish stocks, which use the area for feeding during the summer. The period 1995–2006 had some of the highest biomass of pelagic fish feeding in the Norwegian Sea on record. Here we address the horizontal distribution and overlap between herring, blue whiting and mackerel in this period during the summers using a combination of acoustic, trawl and LIDAR data. A newly developed temperature atlas for the Norwegian Sea is used to present the horizontal fish distributions in relation to temperature. The centre of gravity of the herring distribution changed markedly several times during the investigated period. Blue whiting feeding habitat expanded in a northwestern direction until 2003, corresponding with an...
Tipo: Text
Palavras-chave: Herring; Mackerel; Blue whiting; Temperature; Competition; Interaction.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00079/19018/16602.pdf

Influence du vieillissement d'une population de crépidules sur l'épifaune associée. Influence sur le recrutement
Provedor de dados: 5
Autores: Haubois, Anne-gaëlle.
Crepidula fornicata (slipper Iimpet) is a gastropod mollusc, coming from the North American east coast. Since its accidentaI introduction on french coasts, fifty years ago, C. fomicata invaded several coastal areas of this country and the bay of Saint Brieuc (Brittany -France) is one of the major site affected by the proliferation. Accumulation of dense mats of the slipper limpet contributes to the modification of the bottom structure and affects the substrate's heterogeneity, allowing the settlement of a diversified vagile and sessile epifauna. In this paper, the effects of the C. fornicata population ageing on epifauna assemblages and recruitment are studied. Quantitative and qualitative analysis of epifauna organisms suggests that, the ageing of the C....
Tipo: Text
Palavras-chave: Crepidula fornicata; Vieillissement; Épifaune; Compétition; Baie de Saint-Brieuc; Crepidu/afornicata; Ageing; Epifauna; Competition; Bay of Saint-Brieuc.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00037/14822/12138.pdf

Characterization of food web structure of the upper continental slope of the Celtic Sea highlighting the trophic ecology of five deep-sea fishes
Provedor de dados: 5
Autores: Kopp, Dorothee; Robert, Marianne; Pawlowski, Lionel.
In marine ecosystems, the study of trophic relationships has extensively benefited from the development of stable isotope analyses (SIA) as dietary tracers. SIA are particularly useful in elucidating the structure of deep sea food webs given the constraints involved in obtaining gut-content data from deep trawling. We used carbon and nitrogen stable isotope analyses and Stable Isotope Bayesian Ellipses in R (SIBER) and Stable Isotope Analysis in R (SIAR) routines, to determine the trophic ecology of five deep-sea fishes from the upper continental slope of the Celtic Sea. SIA made it possible to deduce some general tendencies in food-web structure and species trophic interactions and confirmed diet determined by gut-content analysis for the same species, in...
Tipo: Text
Palavras-chave: Competition; Feeding habits; Mixing models; Stable isotope.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00410/52138/52940.pdf

Harmful algae niche responses to environmental and community variation along the French coast
Provedor de dados: 5
Autores: Karasiewicz, Stephane; Chapelle, Annie; Bacher, Cedric; Soudant, Dominique.
Distribution, frequency and intensity of harmful phytoplanktonic species are impacted by changes in environmental conditions. In the Bay of Brest, Alexandrium minutum has been responsible for several harmful algal blooms (HABs) associated with toxin production causing paralytic shellfish poisoning (PSP). Additionally, Lepidodinium chlorophorum causes green water and hypoxia locally in the Bay of Biscay. Previous studies revealed that L. chlorophorum’s success was related to possible competitive exclusion. Therefore, the phytoplankton composition and the environmental conditions should be taken into account. This study aims to assess the combined effect of changes in habitat conditions and community structure with the occurrence of HAB species, on a...
Tipo: Text
Palavras-chave: Alexandrium minutum; Lepidodinium chlorophorum; Subniche; Competition; Indicating species; Spatio-temporal data.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00614/72567/71521.xml

Tidal cycle control of biogeochemical and ecological properties of a macrotidal ecosystem
Provedor de dados: 5
Autores: Cadier, Mathilde; Gorgues, Thomas; Lhelguen, Stephane; Sourisseau, Marc; Memery, Laurent.
In some regions, tidal energy can be a key factor in the generation of variability in physical and biogeochemical properties throughout the water column. We use a numerical model resolving tidal cycles and simulating diversity in phytoplankton to assess the impact of tidal mixing on vertical stability and phytoplankton community (total biomass and diversity) in a macrotidal sea (Iroise Sea, France). Two different time scales have been considered: semi-diurnal and spring/neap tidal cycles. Our results show that the latter is the one primarily influencing the phytoplankton growth conditions by modifying the vertical stratification. During spring tide, the growth is rather light-limited whereas neap tide conditions lead to vertical stabilization and better...
Tipo: Text
Palavras-chave: Macrotidal ecosystem; Spring; Neap tidal cycle; Semidiurnal cycle; Phytoplankton communities; Diversity; Competition.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00395/50612/51325.pdf

Estimation of technical interactions due to the competition for resource in a mixed-species fishery, and the typology of fleets and metiers in the English Channel
Provedor de dados: 5
Autores: Ulrich, Clara; Gascuel, Didier; Dunn, Matthew R; Le Gallic, Bertrand; Dintheer, Christian.
In a multi-gear and multi-species artisanal fishery, the level of technical interactions (i.e. the competitive externalities resulting from a shared exploitation of common resources or fishing grounds) among various fishing units is high. Assessing these technical interactions is of great importance for fishery management, as any control applied to one fishing unit may have positive or negative effects on others. The magnitude and direction of these effects cannot be easily measured, unless all fishing units and species in the fishery are considered simultaneously. Technical interactions are particularly important in the complex artisanal fisheries of the English Channel. Using a bioeconomic model of the English Channel that incorporates all the major...
Tipo: Text
Palavras-chave: Modèle bioéconomique; Compétition; Externalités de stock; Interactions techniques; Typologie; Manche; Bioeconomic model; Competition; Stock externalities; Technical interactions; Typology; English Channel.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00187/29874/28363.pdf

Marine diatoms sustain growth of bivalves in a Mediterranean lagoon
Provedor de dados: 5
Autores: Pernet, Fabrice; Malet, Nathalie; Pastoureaud, Annie; Vaquer, Andre; Quere, Claudie; Dubroca, Laurent.
Carbon stable isotopes and fatty acids were measured in the suspended particulate organic matter (POM) of the Thau lagoon to study its qualitative temporal changes in relation to environmental factors and to identify the food sources of bivalves over a one-yr-cycle in relation to their growth. Reciprocally, the impact of shellfish farming on POM was also studied. Oysters and mussels were sampled and measured for biometry, stable isotopes and fatty acid composition. Water samples were collected at two sites, both inside and outside of the shellfish farming area, to determine concentrations in POM, chlorophyll a (Chl a) and stable isotopes. Carbon isotopes and fatty acids in bivalves reflected seasonal changes in food sources, which varied consistently with...
Tipo: Text
Palavras-chave: Aquaculture; Bivalve; Competition; Feeding ecology; Growth; Trophic markers.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00075/18575/16177.pdf

Alexandrium minutum growth controlled by phosphorus An applied model
Provedor de dados: 5
Autores: Chapelle, Annie; Labry, Claire; Sourisseau, Marc; Lebreton, Carole; Youenou, Agnes; Crassous, Marie-pierre.
Toxic algae are a worldwide problem threatening aquaculture public health and tourism Alexandrium a toxic dinoflagellate proliferates in Northwest France estuaries (i e the Penze estuary) causing Paralytic Shellfish Poisoning events Vegetative growth and in particular the role of nutrient uptake and growth rate are crucial parameters to understand toxic blooms With the goal of modelling in situ Alexandrium blooms related to environmental parameters we first try to calibrate a zero-dimensional box model of Alexandrium growth This work focuses on phosphorus nutrition Our objective is to calibrate Alexandrium minutum as well as Heterocapsa triquetra (a non-toxic dinoflagellate) growth under different rates of phosphorus supply other factors being optimal and...
Tipo: Text
Palavras-chave: Toxic algal blooms; Alexandrium; Phosphorus uptake; Models; Competition; Northwest France.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00018/12901/9905.pdf

Notes on the genus Amphiprion Bloch &amp; Schneider, 1801 (Teleostei: Pomacentridae) and its host sea anemones in the Seychelles
Provedor de dados: 16
Autores: Hartog, J.C. den.
The genus Amphiprion Bloch &amp; Schneider, 1801, is represented in the Seychelles by two species, A. akallopisos Bleeker, 1853, and the endemic A. fuscocaudatus Allen, 1972. Throughout its distributional range Amphiprion akallopisos has exclusively been recorded to associate with the clownfish anemones Heteractis magnifica (Quoy &amp; Gaimard, 1833) and Stichodactyla mertensii Brandt, 1835. During the Netherlands Indian Ocean Programme (NIOP) Seychelles Expedition 19921993 this was confirmed for the Seychelles, although the species was predominantly found with H. magnifica, the most common host anemone in the islands. So far, Amphiprion fuscocaudatus had exclusively been reported as a symbiont of Stichodactyla mertensii. During the NIOP Seychelles...
Tipo: Article / Letter to the editor
Palavras-chave: Seychelles; Indo-West Pacific; Amphiprion; Clownfish anemones; Clownfish/host associations; Host preference; Competition; New records; 42.81.
Ano: 1997
URL: http://www.repository.naturalis.nl/record/319315

Sexual strategies in the newts Triturus cristatus and Triturus marmoratus
Provedor de dados: 16
Autores: Zuiderwijk, Annie.
Courtship display characteristics are described and compared for the newts Triturus cristatus and T. marmoratus and patterns of male competitive behaviour are recognized. In interpreting the data, the operational sex ratio has to be taken into account, which was highly biased towards males in both species, more in T. marmoratus than in T. cristatus. When sexual active, males of cristatus had more encounters than males of marmoratus, whereas the latter spent more time residing mating places. The male’s display towards a female differed in time structure, variability and in behaviour characteristics. T. marmoratus display follows a fixed pattern; males succeeded better in restraining a female than males cristatus did. Courting males cristatus allowed other...
Tipo: Article / Letter to the editor
Palavras-chave: Salamandridae; Triturus; Courtship behaviour; Sexual strategy; Competition.
Ano: 1990
URL: http://www.repository.naturalis.nl/record/504436

Coexistence of surface and cave amphipods in an ecotone environment
Provedor de dados: 16
Autores: Luštrik, R.; Turjak, M.; Kralj-Fišer, S.; Fišer, C.
Interspecific interactions between surface and subterranean species may be a key determinant for species distributions. Until now, the existence of competition (including predation) between these groups has not been tested. To assess the coexistence and potential role of interspecific interactions between surface Gammarus fossarum and subterranean Niphargus timavi, and to determine their micro distributions, we conducted a series of field and laboratory observations. We aimed to determine: (1) species substrate preference, (2) whether the presence of G. fossarum influences the habitat choice of N. timavi, and (3) possible predation effects on micro habitat choice of small juveniles. Throughout a small river in SW Slovenia, N. timavi was predominantly found...
Tipo: Article / Letter to the editor
Palavras-chave: Amphipoda; Cannibalism; Competition; Ecotone; Microhabitat preference; Predation; 42.74.
Ano: 2011
URL: http://www.repository.naturalis.nl/record/377199

First come, first serve: " sit and wait" behavior in dung beetles at the source of primate dung
Provedor de dados: 82
Autores: Jacobs,Jennifer; Nole,Inés; Palminteri,Susanne; Ratcliffe,Brett.
Dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) compete intensively for dung resources, and most species forage in the understory. Here, we describe the unique behavior of one dung beetle species, Canthon aff. quadriguttatus (Olivier), associated with two species of monkeys from Peru. We observed this beetle species on the genital and anal regions of the brown titi monkey, Callicebus brunneus (Wagner), and subsequently falling with dung as the monkeys defecated. The same association was also observed with the bald-faced saki monkey, Pithecia irrorata irrorata (Gray). Using the " sit and wait" at the source behavior, C. quadriguttus may arrive first at the dung resource, possibly out-competing other dung beetle species. This paper is the first report...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Resource partitioning; Phoresy; Niche specialization.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2008000600003

The dynamics of intraguild predation in Chrysomya albiceps Wied. (Diptera: Calliphoridae): interactions between instars and species under different abundances of food
Provedor de dados: 82
Autores: Rosa,Gisele S.; Carvalho,Lidia R. de; Reis,Sergio F. dos; Godoy,Wesley A.C.
The pattern of larval interaction in blowflies confined with Chrysomya albiceps Wied. and C. rufifacies Maquart can be changed in response to the predatory behaviour of the two species to a contest-type process instead of the scramble competition that usually occurs in blowflies. Facultative predation is a frequent behaviour in C. albiceps and C. rufifacies that occurs as an alternative food source during the larval stage. In this study, we investigated the dynamics of intraguild predation by C. albiceps on other fly species in order to analyse interspecific and intraspecific survival in C. albiceps, C. megacephala and C. macellaria Fabricius. The experimental design of the study allowed us to evaluate how factors such as species, density and abundance of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Larval behavior; Blowfly; Competition.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2006000600009

Assembly rules in Muscid Fly assemblages in the grasslands Biome of Southern Brazil
Provedor de dados: 82
Autores: Krüger,Rodrigo F; Carvalho,Claudio J B de; Ribeiro,Paulo B.
The distribution of muscid species (Diptera) in grasslands fragments of southern Brazil was assessed using null models according to three assembly rules: (a) negatively-associated distributions; (b) guild proportionality; and (c) constant body-size ratios. We built presence/absence matrices and calculated the C-score index to test negatively-associated distributions and guild proportionality based on the following algorithms: total number of fixed lines (F L), total number of fi xed columns (F C), and the effect of the average size of the populations along lines (W) for 5000 randomizations. We used null models to generate random communities that were not structured by competition and evaluated the patterns generated using three models: general, trophic...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Community; Competition; Diptera; Muscidae; Niche theory; Null model.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2010000300006

Resource Defense Polygyny by Hetaerina rosea Selys (Odonata: Calopterygidae): Influence of Age and Wing Pigmentation
Provedor de dados: 82
Autores: Guillermo-Ferreira,R; Del-Claro,K.
Current evidence suggests that in Hetaerina damselflies males exhibit lek mating system. In this study, in order to answer if the same occurs in Hetaerina rosea Selys, we manipulated vegetation substrates used as territories and quantified the number of visiting females, males defending territories and fight intensity. We also examined whether body size and wing pigmentation are selectable traits in male-male competition, and if age affects male territorial behavior. Our results showed that males with larger pigmented areas won more contests, independently of body size. Old males changed from territoriality to sneaking strategy. Contrary to other Hetaerina species, males of H. rosea do not display lek behavior, but defend resources according to the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Lek; Territoriality; Behavior.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2011000100011

Factors influencing Serrapinnus notomelas (Characiformes: Characidae) populations in upper Paraná river floodplain lagoons
Provedor de dados: 83
Autores: Piana,Pitágoras Augusto; Gomes,Luiz Carlos; Cortez,Elimaida Mayo.
Identification of variables that influence fish populations is one of the main challenges in ecology. To explore this, data were collected quarterly from February 2000 to November 2001 using seines, along the shore of four isolated lagoons of the upper Paraná River floodplain. Serrapinnus notomelas was selected to assess the effect of abiotic and biotic variables using indirect gradient analysis. Abiotic variables were summarized by principal components analysis (PCA) and then the scores of the axis retained for interpretation were correlated with abundances of S. notomelas. Variables that best explained S. notomelas abundance were surface area of the lagoon, total suspended solids and Secchi depth (these last two, indirectly linked to predation). The most...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Population regulation; Abiotic variables; Competition; Predation.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252006000100008

Feeding dynamics of Cichla kelberi Kullander &amp;amp; Ferreira, 2006 introduced into an artificial lake in southeastern Brazil
Provedor de dados: 83
Autores: Villares Junior,Gilberto Aparecido; Gomiero,Leandro Muller.
The objective of this study was to characterize the seasonally of the diet of Cichla kelberi in an artificial lake in Leme-SP, determining the food items and their relation to the sex and gonadal maturity of the fish sampled. The diet of C. kelberi presents a dynamic in three different periods: winter months were characterized by low feeding activity and a high concentration of undetermined fish; increase in feeding activity occurred in the spring, with Tilapia sp. being the dominant food item; and a high rate of cannibalism was observed in the summer and early fall. The plasticity in the composition of the diet was marked by quantity of prey available during the different periods of the year, and the reproductive period.
Tipo: Info:eu-repo/semantics/other
Palavras-chave: Seasonality; Cannibalism; Predation; Competition.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252010000400011

Is coexistence between non-native and native Erythrinidae species mediated by niche differentiation or environmental filtering? A case study in the upper Paraná River floodplain
Provedor de dados: 83
Autores: Pereira,Larissa S.; Mise,Fábio T.; Tencatt,Luiz F. C.; Baumgartner,Matheus T.; Agostinho,Angelo A.
ABSTRACT The limiting similarity theory predicts that divergence in the functional traits of native and introduced species is an essential component in species establishment, as introduced species must occupy a niche that is unoccupied by resident species. On the other hand, the environmental filtering hypothesis predicts convergence between introduced and native species, as both possess traits that make them adapted to the local abiotic environment. Morphology, spatial co-occurrence, diet, feeding selectivity, and niche breadth and overlap of Erythrinidae were evaluated to detect possible mechanisms acting in the coexistence between non-native and native species. Native (Hoplias sp. B and Hoplias cf. malabaricus) and non-native (Hoplerythrinus...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Co-occurrence; Fish feeding; Morphology; Predation.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252017000200218

Natural and semi-natural grasslands in Japan with special reference to Sasa dwarf bamboo grasslands
Provedor de dados: 19
Autores: Konno, Yasuo; 紺野, 康夫.
2003年8月28日とかちプラザで開催､日本ユネスコ国内委員会主催の帯広農村開発教育国際セミナー(OASERD)国際連合ユネスコアジア太平洋地域教育開発計画事業(APEID)シンポジウム「地球にやさしい農業をめざして : 緑地回復と持続的農業」講演資料
Palavras-chave: Competition; Regulation of leaf production; Light; Water content of soil.
Ano: 2003
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/1907

Temporal differences in breeding site use between tits and mice
Provedor de dados: 19
Autores: Suzuki, Kei K.; Yoshida, Tomoya; Yamane, Yutaka; Shimamoto, Tatsuki; Furukawa, Ryuji G.; Yanagawa, Hisashi.
Describing the interactions among cavity breeders is key to understanding their breeding ecology. In this study　the temporal difference in cavity use between the great tit, Parus major (Linnaeus, 1758) and the small Japanese field mice, Apodemus argenteus (Temminck, 1845) is investigated, as a first step for clarifying the interaction between bird and mammal cavity breeders. Forty-seven nest boxes were installed on tree trunks in two urban forests of Hokkaido Island, Japan, and the breeding nests of tits and mice were found in 34 and 11 boxes, respectively. The tits used the nest boxes throughout the breeding season, from May to July. In contrast, mice breeding nests were found in the last half of the breeding season, from July to October. Our results...
Palavras-chave: Bird-mammal interaction; Breeding ecology; Competition; Reproduction strategy; Tree cavities.
Ano: 2017
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4562

Interacciones entre corales y macroalgas: dependencia de las especies involucradas
Provedor de dados: 20
Autores: Márquez, J.C.; Díaz, J.M.
Macroalgae proliferation on coral reefs has been a recognized phenomenon for the past two decades and is generally entitled to the human activities on the coasts. Even thought, the role of competition in this process is not clear and it has been assumed that algae are competitively superior to corals, even when it has been demonstrated that this is not always the case. It is probable that the result of coral-macroalgae depends upon the species involved. The goal of this study was to demonstrate that there is a dependence relation between interaction category and interacting species. In order to resolve this, quantifications of interactions per category along 20 m transects were done on three representative localities at the Archipielago de San Bernardo....
Tipo: Journal Contribution
Palavras-chave: Coral; Interactions; Competition; Benthos; Benthos; Http://aims.fao.org/aos/agrovoc/c_878.
Ano: 2005
URL: http://hdl.handle.net/1834/2013

Macrophytes of Lake Victoria and succession after invasion of Water Hyacinth
Provedor de dados: 20
Autores: Omondi, R.; Kusewa, Mwende.
The distribution of Lake Victoria (Kenya) macrophytes is described. Succession of macrophytes in the lake became more dramatic and dynamic after invasion of water hyacinth. The weed pushes and smothers other free-floating macrophytes like Pistia stratiotes. It then provides substrates for the emergent Vossia cuspidata, which later reduces its population by competition for light and nutrients. The noxious weed is believed to have led to extinction of Azolla nilotica in the lake.
Tipo: Proceedings Paper
Palavras-chave: Aquatic plants; Ecological succession; Introduced species; Species extinction; Inland waters; Water reservoirs; Geographical distribution; Emergent vegetation; Competition; Water bodies; Aquatic plants; Water hyacinth; Http://aims.fao.org/aos/agrovoc/c_559; Http://aims.fao.org/aos/agrovoc/c_15267.
Ano: 2006
URL: http://hdl.handle.net/1834/1496

Competition between the sibling species &lt;i&gt;Tisbe holothuriae&lt;/i&gt; and &lt;i&gt;T. battagliai&lt;/i&gt; (Harpacticoida)
Provedor de dados: 27
Autores: Bergmans, M.; Janssens, P.P.M.
The influence of the salinity on the performance of the sibling species &lt;i&gt;Tisbe holothuriae&lt;/i&gt; and &lt;i&gt;T. battagliai&lt;/i&gt; in pure and mixed cultures was studied, using laboratory stocks adapted to 32 pro mille for over 175 generations. Cohort studies show that &lt;i&gt;T. holothuriae&lt;/i&gt; has higher growth rates (R&lt;sub&gt;0&lt;/sub&gt; and r) at 32 pro mille, &lt;i&gt;T. battagliai&lt;/i&gt; at 20 pro mille. The latter's life cycle is much less affected by the difference in salinity. 'De Wit' replacement series were used to study competitive interactions. Without water renewal, &lt;i&gt;T. holothuriae&lt;/i&gt; eliminates its sibling species in less than 2 generations, apparently through chemical interference. With water...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Growth; Marine crustaceans; Phenology; Salinity; Sexual reproduction; Sibling species; Harpacticoida; Tisbe battagliai; Tisbe holothuriae.
Ano: 1988
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3121

The influence of competition and predation on production of meiobenthic copepods
Provedor de dados: 27
Autores: Heip, C.H.R.
An assemblage of meiobenthic copepods was monitored twice monthly between 1968 and 1976 in a shallow brackish water habitat. Four species dominated and accounted for nearly all the production. All species have only one or two generations per year and each peak has similar dynamic characteristics. Production is determined primarily by the number of generations, and it is suggested that competition and predation determine the life-history characteristics.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Predation; Copepoda [copepods].
Ano: 1980
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=6999

Scanning electron microscopy of the interaction between Cryptococcus magnus and Colletotrichum gloeosporioides on papaya fruit
Provedor de dados: 86
Autores: Capdeville,Guy de; Souza Júnior,Manoel Teixeira; Santos,Jansen Rodrigo Pereira; Miranda,Simoni Paula; Caetano,Alexandre Rodrigues; Falcão,Rosana; Gomes,Ana Cristina Menezes Mendes.
The objective of this work was to investigate possible modes of action of the yeast Cryptococcus magnus in controlling anthracnose (Colletotrichum gloeosporioides) on post harvested papaya fruits. Scanning electron microscopy was used to analyze the effect of the yeast on inoculations done after harvest. Results showed that C. magnus is able to colonize wound surfaces much faster than the pathogen, outcompeting the later for space and probably for nutrients. In addition, C. magnus produces a flocculent matrix, which affects hyphae integrity. The competition for space and the production of substances that affect hyphae integrity are among the most important modes of action of this yeast.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carica papaya; Anthracnose; Antagonist yeast; Biological control; Competition.
Ano: 2007
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2007001100004

Fitness Cost and Competitive Ability to Different Ploidy Levels in Ryegrass Genotypes
Provedor de dados: 87
Autores: SCHMITZ,M.F.; CECHIN,J.; HENCKES,J.R.; PIASECKI,C.; AGOSTINETTO,D.; VARGAS,L.
ABSTRACT: The intergenotypic competition of tetraploid ryegrass with natural diploid population may be a tool to reduce the frequency of resistant individuals in an area. This study aimed to identify and compare the phenological development, fitness cost, and competitive ability between diploid and tetraploid ryegrass genotypes. Genotypes were grown in pots, and the morphological variables of genotype growth were assessed every 15 days up to 120 days after emergence to evaluate the fitness cost. Phenological development and seed yield components were measured in a single time together with the fitness cost. Competitive ability was determined in a replacement-series experiment with proportions of tetraploid and diploid ryegrass, in which the number of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lolium multiflorum; Competition; Diploid; Tetraploid; Integrated weed management.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100189

Density and sowing season of two Brachiaria species on the soybean culture
Provedor de dados: 87
Autores: Saraiva,A.S.; Erasmo,E.A.L.; Mata,J.F.; Dornelas,B.F.; Dornelas,D.F.; SILVA,J.I.C.
The aim of this study was to evaluate the growth and yield of soybean cultivar M-8766 in consortium with Brachiaria brizantha. BRS Piata and Brachiaria ruziziensis at different densities and sowing dates. The experimental design was randomized blocks with treatments arranged in a factorial 2 x 2 x 3 with four replications. Used as factors grass species (Brachiaria brizantha Piata and Brachiaria ruziziensis BRS) intercropped with soybean M-8766, sowing dates (12 and 24 days after soybean emergence) and three seeding rates (0, 5, 10 kg ha-1 of seed). At 71 days after soybean emergence were evaluated plant height, stem diameter, dry mass of leaves, stems and shoots, and 4 months after sowing determined the weight of 100 grains and soybean yield. The results...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Glycine max; Brachiaria brizantha; Brachiaria ruziziensis; Crop-livestock integration; System holy faith.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000300009

Multispecies weed competition and their economic threshold on the wheat crop
Provedor de dados: 87
Autores: Gherekhloo,J.; Noroozi,S.; Mazaheri,D.; Ghanbari,A.; Ghannadha,M.R.; Vidal,R.A.; Prado,R. de.
Two field experiments were conducted to evaluate the effects of multispecies weed competition on wheat grain yield and to determine their economic threshold on the crop. The experiments were conducted in 2002, on two sites in Iran: at the Agricultural Research Station on Ferdowsi University of Mashhad (E1) and on the fields of Shirvan's Agricultural College (E2). A 15 x 50 m area of a 15 ha wheat field in E1 and a 15 x 50 m area of a 28 ha wheat field in E2 were selected as experimental sites. These areas were managed like other parts of the fields, except for the use of herbicides. At the beginning of the shooting stage, 30 points were randomly selected by dropping a 50 x 50 cm square marker on each site. The weeds present in E1 were: Avena ludoviciana,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Weed interference; Competition; Grain yield; Mathematical regression.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582010000200002

Soybeans Competitiveness with Morning Glory
Provedor de dados: 87
Autores: PICCININI,F.; MARTIN,T.N.; MACHADO,S.L.O.; KRUSE,N.D.; SCHMATZ,R.
Weeds interfere negatively on development, yield and quality of soybeans (Glycine max). Inadequate weed control by herbicide use can select for resistant or tolerant biotypes, leading to a shift in the weed flora. An example is the increase of incidence of morning glory (Ipomoea spp.) in soybeans growing areas in South Brazil. The aim of this study was to determine the competitiveness of soybeans intercropped with I. triloba, I. indivisa and I. purpurea through a replacement experiments series. Greenhouse experiments were conducted in a completely randomized design with four replications. The first experiment was carried out aiming to get the plant population while total plant dry mass remained constant. Other experiments were done under replacement series...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; I. triloba; I. indivisa; I. purpurea; Replacement series.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000100025

Relative Competitiveness of Common Bean Cultivars in Coexistence with Volunteer Corn
Provedor de dados: 87
Autores: AGUIAR,A.C.M.; BASSO,C.J.; SILVA,D.R.O.; GHELLER,D.P.; NOVELLO,B.D.; RIEDER,E.
ABSTRACT: This study evaluated the relative competitiveness of two common bean cultivars in coexistence with volunteer corn emerging at different times in different proportions of plants in the association. Firstly, for both beans and volunteer corn, the plant population was determined in which the final production of dry biomass becomes constant (24 plants pot-1). A completely randomized experiment design, with five replicates, was carried out in a 2×2×5 factorial scheme, involving two common bean cultivars (IPR Gralha and Fepagro Triunfo), two emergence times of volunteer corn plants (-7 and 0 days in relation to beans) and five proportions of plants in the association (100:0, 75:25, 50:50, 25:75 and 0:100). At 35 days after bean emergence, measurements...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Phaseolus vulgaris; Zea mays; Volunteer plants; Competition; Emergence periods; Replacement series.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100294

Modeling light interception and distribution in mixed canopy of common cocklebur (Xanthium stramarium) in competition with corn
Provedor de dados: 87
Autores: Vazin,F.; Hassanzadeh,M.; Madani,A.; Nassiri-Mahallati,M.; Nasri,M.
The aim of this study was to model light interception and distribution in the mixed canopy of Common cocklebur (Xanthium stramarium) with corn. An experiment was conducted in factorial arrangement on the basis of randomized complete blocks design with three replications in Gonabad in 2006-2007 and 2007-2008 seasons. The factors used in this experiment include corn density of 7.5, 8.5 and 9.5 plants per meter of row and density of Common cocklebur of zero, 2, 4, 6 and 8 plants per meter of row. INTERCOM model was used through replacing parabolic function with triangular function of leaf area density. Vertical distribution of the species' leaf area showed that corn has concentrated the most leaf area in layer of 80 to 100 cm while Common cocklebur has...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modeling; Competition; Common cocklebur; Corn; Light.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582010000300001

Physiological Response of Maize and Weeds in Coexistence
Provedor de dados: 87
Autores: BARROS,R.E.; FARIA,R.M.; TUFFI SANTOS,L.D.; AZEVEDO,A.M.; GOVERNICI,J.L.
ABSTRACT This study aimed at evaluating the physiology of maize and weeds when living under different densities. The randomized block design with 4 replications was used. The factorial scheme 5 x 2 + 1 and 5 x 3 was adopted, for maize and weeds respectively, corresponding to weed species (Bidens pilosa, Commelina benghalensis, Urochloa brizantha, Sorghum arundinaceum and Ipomoea triloba) and infestation density (control, 15 and 30 plants m-2). Weeds were kept in coexistence with the maize hybrid DKB 390 PRO 2, with an additional treatment for maize plants absent of competition. It was kept in coexistence with maize hybrid DKB 390 PRO 2 besides an additional treatment with maize plants absent of competition. On day 45 and 60 after maize planting (DAP)...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Zea mays; Urochloa brizantha; Sorghum arundinaceum; Photosynthetic rate; Transpiration; Competition.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582017000100223

Interference of Morning Glory in Soybean Yield
Provedor de dados: 87
Autores: PICCININI,F.; MACHADO,S.L.O.; MARTIN,T.N.; KRUSE,N.D.; BALBINOT,A.; GUARESCHI,A.
ABSTRACT: Weed control using herbicides with the same mechanism of action can encourage the emergence of resistant biotypes or tolerant plants. An example of this is the occurrence of morning-glory (Ipomoea sp.) in soybean crops in southern Brazil. In this sense, the aim of this study was to quantify the losses arising from two species of morning-glory weeding coexisting with soybean crop. A field study was conducted in the 2013/2014 season. The experimental design was a randomized block with four replications, with treatments being distributed in a factorial arrangement (2x2x5), which assessed the effect of competition on two soybean cultivars (TEC6029 and TEC7849) of morning-glory species (I. triloba and I. purpurea) in different population (0, 4, 8, 16...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Ipomoea triloba; Ipomoea purpurea; Glycine max.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100262

Weed Interference in Okra Crop in the Organic System During the Dry Season
Provedor de dados: 87
Autores: SANTOS,R.N.V.; PIRES,T.P.; MESQUITA,M.L.R.; CORREA,M.J.P.; SILVA,M.R.M.
ABSTRACT: In organic systems during the dry season, competition of weeds with okra increases the critical period of interference of these species and yield losses. The objective of this research was to determine the critical period of weed interference in organic okra during the dry season in São Luís - MA. The experiment was conducted from October/2014 to January/2015 in randomized blocks, with four replicates. The treatments were the periods of 07, 14, 21, 28, 35, 42 days after the transplanting of the crop with control and coexistence of the infesting community. The species with the highest importance value index were Cynodon dactylon, Eleusine indica, Amaranthus spinosus and Commelina benghalensis. The CPWI was 04 to 53 days after transplanting and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Abelmoschus esculentus (L.) Moench.; Competition; Water deficit; Weed community.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100214

Urochloa brizantha Interference in the Phaseolus vulgaris Radicular System Fertilized with Phosphorus
Provedor de dados: 87
Autores: FREITAS,A.F.; MACIEL,J.C.; SILVA,M.M.; SANTOS,J.B.
ABSTRACT: Interference between root systems occurs below the ground surface long before the competition between plants is expressed in the shoot. Nutrients stand out for being limited in the soil, requiring supplementation, especially phosphorus. Thus, this study aimed at estimating, from sowing, visual characteristics in the root systems of bean plants from the Carioca variety (Phaseolus vulgaris) when in competition with brachiaria (Urochloa brizantha), considering also the application of phosphorus P2O5. A factorial design with six treatments was used resulting from the combination of three cultivation schemes (beans in isolated crops or in competition with one or two brachiaria plants), and the application or not of phosphate fertilizer (90 kg ha-1 of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Rhizotron; Weed.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100252

Does the resistance to glyphosate herbicide affect the competitive ability of ryegrass with soybean?
Provedor de dados: 87
Autores: Oliveira,C.; Agostinetto,D.; Vargas,L.; Ávila,L.A.; Tarouco,C.P.
The objective this work was to investigate the competitive ability between resistant and susceptible ryegrass biotypes and of these with soybean crop. Four experiments were carried under greenhouse, in a completely randomized design with four replications, in 2011 and 2012. Treatments were arranged in additive series and replacement series assay. In each series, the proportions among ryegrass resistant and susceptible plants related to soybean were: 100:0, 75:25, 50:50, 25:75 e 0:100. Leaf area and shoot dry mass were evaluated. Competitiveness statistical analysis consisted in applying diagrams to the replacement series and alternative interpretations of the competitiveness indexes. The soybean crop had equivalent competitiveness to the susceptible...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lolium multiflorum; Glycine max; Competition.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582014000100021

Competitive ability of soybean cultivars with horseweed (Conyza bonariensis)
Provedor de dados: 87
Autores: Trezzi,M.M.; Balbinot Jr.,A.A.; Benin,G.; Debastiani,F.; Patel,F.; Miotto Jr.,E.
The existence of large areas infested with populations of Conyza spp. resistant to glyphosate in Brazil demands appropriate and integrated management strategies. This experiment aimed to identify soybean cultivars with greater competitive ability with horseweed plants and to determine plant characteristics associated with this ability. The experiment was arranged in a randomized complete block design with split plots. Seven soybean cultivars (CD 225 RR, BRS 232, CD 226 RR, NK 7054 RR, BMX Apollo RR, BRS 245 RR and BRS 255 RR) were allocated in the plots, and two interference situations (absence and 13.3 plants of Conyza m-2, transplanted seven days before soybean planting) in the subplots. The average yield loss due to competition with horseweed was 25%....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Conyza spp.; Interference; Competition; Grain yield.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000300006

Weed Interference on Productivity of Bell Pepper Crops
Provedor de dados: 87
Autores: ULJOL,L.H.O.; BIANCO,S.; FILHO,A.B.C.; BIANCO,M.S.; CARVALHO,L.B.
ABSTRACT: The objective of this work was to determine the interference periods of weeds of the bell pepper cultivar ‘Dahra’. Two experiments were conducted during the years 2014/15 (harvest with lower rainfall) and 2015/16 (harvest with higher rainfall). The treatments consisted of 11 growing periods of cohabitation and weed control with ‘Dahra’ bell peppers: 14, 28, 42, 56, 70, 84, 98, 112, 126, 140 and 154 days after transplanting (DAT). For the determination of the interference periods, the productivity data were analyze using the Boltzmann sigmoidal regression model. The main weeds were Eleusine indica, Brachiaria plantaginea, Digitaria nuda and Nicandra physaloides for presenting high biomass and relative density. The concomitance of these weeds...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Capsicum annuum; Competition; Coexistence.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100247

Competitiveness of alexandergrass or Bengal dayflower with soybean
Provedor de dados: 87
Autores: Dias,A.C.R.; Carvalho,S.J.P.; Marcolini,L.W.; Melo,M.S.C.; Christoffoleti,P.J.
Weeds compete with field crops mainly for water, light and nutrients, and the degree of competition is affected by the weed density and the intrinsic competitive ability of each plant species in coexistence. The objective of this research was to compare the competitiveness of alexandergrass (Brachiaria plantaginea) or Bengal dayflower (Commelina benghalensis) in coexistence with soybean, cv. M-Soy 8045. A factorial experiment (2 x 5) with two weed species and five competition proportions was carried out in a completely randomized design with four replicates. Proportions were based on a replacement series competition design, always maintaining the total density of four plants per 10 L plastic pots, which corresponded to 60 plants m ². The weed-crop...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Glycine max; Brachiaria plantaginea; Commelina benghalensis; Competition; Dry mass; Substitutive series.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582010000300008

Weed Interference on ‘Prata-Anã’ Banana Production
Provedor de dados: 87
Autores: SANTOS,G.C.; MAIA,V.M.; ASPIAZÚ,I.; PEREIRA,M.C.T.; DONATO,S.L.R.; NOBRE,D.A.C.
ABSTRACT: In the state of Minas Gerais, the northern region is one of the main banana production cores. Weed interference can reduce crop growth and, consequently, lead to reduced yield and fruit quality. Therefore, the objective of this study was to evaluate the interference of weeds in the production of the first and second cycles of ‘Prata-Anã’ bananas. The experimental design was randomized blocks, with ten treatments and three replicates, evaluated in two crop cycles. The treatments were ten periods of weed control, from planting: without control; control throughout the whole experimental period; control only in the first month after planting; control until the second; third; fourth; fifth; sixth; eighth and tenth months after planting. The agronomic...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Musa spp.; Competition; Control.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100150

Effects of weed species competition on the growth of young coffee plants
Provedor de dados: 87
Autores: Ronchi,C.P.; Silva,A.A.
The effects of competition of seven weed species on the growth of coffee plants were evaluated under greenhouse conditions. Thirty days after coffee seedling transplantation into 12 L pots with soil level area of 6.5 dm², weeds were transplanted into or sown in those pots, at densities of 0, 1, 2, 3, 4 and 5 plants per pot. Competition or weedy periods from weed transplantation or emergence to plant harvesting, at weed pre-flowering stage, were: 77 days - Bidens pilosa, 98 days - Brachiaria decumbens, 180 days - Commelina diffusa, 82 days - Leonurus sibiricus, 68 days - Nicandra physaloides, 148 days - Richardia brasiliensis and 133 days - Sida rhombifolia. Coffee plant height, stem diameter, leaf number and shoot dry matter were determined. Effects of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Density; Coffea arabica; Competition; Weedy period.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582006000300001

Weed Interference Periods in Early Wheat in the Midwest of Paraná
Provedor de dados: 87
Autores: SILVA,A.A.P.; OLIVEIRA NETO,A.M.; NAIARA,G.; KARPINSKI,R.A.K.; MACIEL,C.D.G.
ABSTRACT Several factors can influence wheat crop yield, they include the interference imposed by weeds is one of the most important. The objective of this study was to evaluate the critical periods of weed interference in early wheat in the midwest of the state of Paraná, Brazil. The experiment was conducted in an experimental area located in Campo Mourão - PR, during the year 2013, using the BRS Pardela cultivar. The treatments consisted of periods of coexistence and weed control in wheat. Periods of coexistence and control were 0, 7, 14, 28, 35 and the whole cycle at days after crop emergence (DAE). Number of reproductive tillers per plant, spike length, number of spikelets per spike, plant height and wheat crop yield, were significantly affected by...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Raphanus raphanistrum; Triticum aestivum.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000200291

Effects of weed control through cowpea intercropping on mayze morphology and yield
Provedor de dados: 87
Autores: Gomes,J.K.O.; Silva,P.S.L.; Silva,K.M.B.; Rodrigues Filho,F.F.; Santos,V.G.
Intercropping combined with competitive maize cultivars can reduce the use of herbicides to control weeds. The objective of this work was to evaluate the effects of intercropping cowpea and maize, as well as hand-weeding on maize morphology and yield. The experimental design was in randomized complete blocks, with treatments arranged in split-plots and five replications. The plots consisted of four maize cultivars (BA 8512, BA 9012, EX 4001, EX 6004) and the split-plots consisted of the following treatments: no-weeding; twice hand-weeding (20 and 40 days after sowing); and intercropping with cowpea ('Sempre Verde' cultivar), both maize and cowpea sown at the same time. The variables evaluated were: maize fresh green ears and grain yield; characteristics of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Zea mays L.; Green ears; Grain yield; Competition; Vigna unguiculata (L) Walp.
Ano: 2007
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582007000300001

Competitive Ability of Santa-Maria (Parthenium hysterophorus L.) with Spring Maize
Provedor de dados: 87
Autores: REHMAN,A.; QAMAR,R.; FAROOQ,M.; QAMAR,J.; HASSAN,F.
ABSTRACT: In recent decades, allelopathy has gained considerable attention in sustainable agricultural systems. In the current situation, an attempt has been made to investigate the optimal competition period for weed control in maize. Experiments were designed in randomized complete block design and Parthenium hysterophorus was naturally infested in experimental plots during the spring season 2014 to determine the critical competition period for weed control in maize. The relations between grain yield and different competition durations were determined via regression analyses. The experiment comprised seven treatments viz, control treatment, competition for 30, 45, 60, 75, 90 and 105 days after emergence. The results suggested that a weed-free period...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Weeds; Yields.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100252

Phytosociological Survey and Weed Interference in Eggplants Cultivation1
Provedor de dados: 87
Autores: MARQUES,L.J.P.; BIANCO,S.; C. FILHO,A.B.; BIANCO,M.S.
ABSTRACT Eggplants are vegetables of great importance in the South and Southeast regions of Brazil, which are subject to interference from weeds. In order to collaborate with weed management in this vegetable, this study was carried out to determine the periods of weed interference in growing eggplants. The study was conducted in the Brazilian municipality of Jaboticabal, SP, at the Faculty of Agricultural and Veterinary Sciences, UNESP [Universidade Estadual Paulista "Júlio de Mesquita Filho" (São Paulo State University)], in the period from February to July 2013. The experiment was arranged in a randomized block design with 22 treatments, three replications divided in 11 periods of coexistence and weed control with eggplants: 14, 28, 42, 56, 70, 84, 98,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Solanum melongena; Competition; Productivity; Weed community.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000200309

Modeling of weeds interference periods in bean
Provedor de dados: 87
Autores: Parreira,M.C.; Barroso,A.A.M.; Pereira,F.C.M.; Alves,P.L.C.A.
The research objective was to determine the effects of spacing and seeding density of common bean to the period prior to weed interference (PPI) and weed period prior to economic loss (WEEPPEL). The treatments consisted of periods of coexistence between culture and the weeds, with 0 to 10, 0 to 20, 0 to 30, 0 to 40, 0 to 50, 0 to 60, 0 to 70, and 0 to 80 days and a control maintained without weeds. In addition to the periods of coexistence, there were still studies with an inter-row of 0.45 and 0.60 m, 10 and 15 plants m-1. The experimental delineation used was randomized blocks with four repetitions per treatment. The grain productivity of the culture had a reduction of 63, 50, 42 and 57% when the coexistence with the weed plants was during the entire...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Phaseolus vulgaris; Competition; PPI; WEEPPEL.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582012000400004

Weed Interference in Semi-Erect and Semi-Prostate Cowpea Cultivars
Provedor de dados: 87
Autores: CASTRO,T.S.; ROCHA,P.R.R.; BARRETO,G.F.; MAIA,S.S.; ALBUQUERQUE,J.A.A.; ALVES,J.M.A.
ABSTRACT: This study aimed to determine weed interference periods in semi-erect and semi-prostrate cowpea cultivars. Two simultaneous experiments were conducted with the cowpea cultivars BRS Guariba (semi-erect) and BRS Aracê (semi-prostrate). The experimental design was a randomized block design with four replications in a 7 × 2 factorial scheme, seven periods × two weed management (control and coexistence). Control and coexistence periods consisted of 0, 0-8, 0-16, 0-24, 0-32, 0-45, and 0-60 days after emergence (DAE) for the semi-erect cultivar and 0, 0-8, 0-16, 0-24, 0-32, 0-45, and 0-64 DAE for the semi-prostrate cultivar. Competition throughout the cycle reduced productivity by up to 39.81% for BRS Guariba and 37.27% for BRS Aracê. The cultivars BRS...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Vigna unguiculata; Competition; Interference periods.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100277

GROWTH AND YIELD RESPONSE OF MAIZE (Zea mays) TO INTER AND INTRA-ROW WEED COMPETITION UNDER DIFFERENT FERTILIZER APPLICATION METHODS
Provedor de dados: 87
Autores: MAQBOOL,M.M.; TANVEER,A.; ALI,A.; ABBAS,M.N.; IMRAN,M.; AHMAD,M.; ABID,A.A.
A field experiment was conducted for two consecutive years to study the effect of fertilizer application methods and inter and intra-row weed-crop competition durations on density and biomass of different weeds and growth, grain yield and yield components of maize. The experimental treatments comprised of two fertilizer application methods (side placement and below seed placement) and inter and intra-row weed-crop competition durations each for 15, 30, 45, and 60 days after emergence, as well as through the crop growing period. Fertilizer application method didn't affect weed density, biomass, and grain yield of maize. Below seed fertilizer placement generally resulted in less mean weed dry weight and more crop leaf area index, growth rate, grain weight...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Fertilizer; Grain yield; Maize; Plant growth.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000100047

Adaptive value of ryegrass biotypes with low-level resistance and susceptible to the herbicide fluazifop and competitive ability with the wheat culture
Provedor de dados: 87
Autores: Fraga,D.S.; Agostinetto,D.; Vargas,L.; Nohatto,M.A.; Thürmer,L.; Holz,M.T.
Ryegrass is the main weed in wheat crop, causing yield loss due to competition by environmental resources. The objectives of this study were to estimate the fitness cost of ryegrass biotypes with low-level resistance and susceptible to fluazifop and to investigate the relative competitive ability of these biotypes between themselves and against the crop. Thus, fitness cost and competitive ability experiments were conducted under greenhouse conditions. For the fitness cost experiments, the low-level resistant ryegrass biotypes and those susceptible to fluazifop were used. For competitive ability, the treatments were arranged in a replacement series, with five proportions of the wheat cultivar FUNDACEP Horizonte and the low-level resistant and susceptible...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Weed; Competition; Lolium multiflorum.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000400014

Interference of Sorghum sudanense and Eleucine indica in the soybean and corn cultivation
Provedor de dados: 87
Autores: Rizzardi,M.A.; Wandscheer,A.C.D.
The natural infestations are composed of numerous species that compete for environmental resources such as water, light, nutrients and space. The objective of this study was to evaluate the interference of mixed infestations Sorghum sudanense (sudangrass) and Eleusine indica (goosegrass) in the presence of soybean and corn. The experimental design was completely randomized with four replications and the experimental units consisted of plastic pots with a volume capacity of 8 L. The treatments were associations of plants S. sudanense and E. indica in the proportions 8:0, 6:2, 4:4,2:6 and 0:8, respectively, corresponding to 100, 75, 50, 25 and 0% S. sudanense and the reverse for E. indica. In all treatments remained constant four soybean or corn plants per...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Sorghum sudanense; Eleusine indica; Competitive hability.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582014000100003

Residual herbicides increase the period prior to interference in soybean cultivars
Provedor de dados: 87
Autores: Rizzardi,Mauro A.; Rockenbach,Ana P.; Schneider,Theodoro.
Abstract  Background:  The pre-emergence herbicides diclosulam and flumioxazin are used to weed control in soybean. We hypothesized management of the new emergence of weeds in the early development stages of the soybean could alter the periods of interference. Thus, the period prior to interference allows and increases the canopy closure spaces before the critical period and disfavors the development of weeds inside the vegetative canopy.  Objective:  This study aimed to evaluate whether the period prior to interference of soybean cultivars was altered due to the application of residual pre-emergence herbicides.  Methods: Two experiments were conducted with the soybean cultivars ‘NA 5909 RG’ and ‘P95R51’. One day before sowing in the main plots, the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Interference periods; Pre-emergence; Competition; Weeds.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100335

Period of Weed Interference in Guarana Crop
Provedor de dados: 87
Autores: SOARES,D.O.P.; ALBERTINO,S.M.F.; SOUZA,F.C.P.; SANTOS,A.F.; SILVA,J.F.
ABSTRACT: Guarana is a plant native to the Amazon region that produces the fruit known as guarana. Guarana production is carried out by small farmers and is a source of income for thousands of people in rural and urban areas. The interference caused by the competition between weeds and guarana is an important limiting factor of its production. Despite its economic and social importance, there are few studies on the management of weeds in this species. Thus, this research aimed to study the effects of weed interference on guarana yield in different periods. This study was performed in Maués, AM, in the 2014 and 2015 seasons. The experimental design was a randomized block design with eight treatments and four blocks. Treatments consisted of a combination of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Critical period; Weeds; Competition; Paullinia cupana.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100267

Competitive ability of corn in coexistence with goosegrass
Provedor de dados: 87
Autores: Wandscheer,A.C.D.; Rizzardi,M.A.; Reichert,M.
Competition between plants is one of the main interferences that occurs in agricultural systems and accounts for significant crop yield reductions. The aim of this study was to assess the competitive ability of corn in coexistence with the weed species Eleusine indica. The experiments were conducted in a greenhouse, in the growing season 2010/2011, and were arranged in a completely randomized design with four replications. The experimental units consisted of plastic pots with a volumetric capacity of 8 L. Treatments were arranged in a replacement series with five proportions of corn plants and weed: 100:0, 75:25, 50:50, 25:75, and 0:100, respectively, with a constant population of eight plants per pot, at the end of each treatment. The competitiveness...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Weed; Eleusine indica; Zea mays.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000200005

Optimizing the width of strip weeding in arabica coffee in relation to crop age
Provedor de dados: 87
Autores: Araújo,FC.; Ronchi,C.P.; Almeida,W.L.; Silva,M.A.A.; Magalhães,C.E.O.; Good-God,P.I.V.
The aim of this study was to determine the weed strip control (WSC) required for adequate coffee growth after transplanting. A non-irrigated, field-planted (spaced 3.80 x 0.70 m) crop was used. The experimental design was a randomized block, with four replicates. The treatments were arranged in a 9 x 18 split-plot design to test the WSC of 0, 15, 30, 45, 60, 90, 120, 150, and 190 cm, which involved continuously hand-weeding at each side of the coffee row, and 18 coffee growth measurements. Multiple regression analyses were carried out relating to growth-variables as a function of both WSC and growth-evaluation times. Brachiaria decumbens was the main weed accomplishing 88.5% of the total weed dry mass. The minimum width of the WSC increases as the crop...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Coffea arabica; Competition; Interference; Surinam grass; Weed management; Weedy periods.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582012000100015

Fitness Cost and Competitive Ability of Ryegrass Susceptible and with Multiple Resistance to Glyphosate, Iodosulfuron-Methyl, and Pyroxsulam
Provedor de dados: 87
Autores: HENCKES,J.R.; CECHIN,J.; SCHMITZ,M.F.; PIASECKI,C.; VARGAS,L.; AGOSTINETTO,D.
ABSTRACT: Ryegrass is an important weed in wheat cultivations due to the evolution of resistance to different mechanisms of action. This study aimed to compare the phenological development, fitness cost, and competitive ability between ryegrass biotypes susceptible and with multiple resistance to 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs) and acetolactate synthase (ALS) inhibiting herbicides. Fitness cost and phenological development were evaluated from biotypes grown in pots, and morphological growth variables were determined up to 140 days after emergence. Phenological development was evaluated with a fitness cost. Competitive ability was determined in a replacement-series experiment with proportions of resistant and susceptible ryegrass. The...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lolium multiflorum; EPSPs; ALS; Competition.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100288

Soil microorganisms and their role in the interactions between weeds and crops
Provedor de dados: 87
Autores: Massenssini,A.M.; Bonduki,V.H.A.; Melo,C.A.D.; Tótola,M.R.; Ferreira,F.A.; Costa,M.D.
The competition between weeds and crops is a topic of great interest, since this interaction can cause heavy losses in agriculture. Despite the existence of some studies on this subject, little is known about the importance of soil microorganisms in the modulation of weed-crop interactions. Plants compete for water and nutrients in the soil and the ability of a given species to use the available resources may be directly affected by the presence of some microbial groups commonly found in the soil. Arbuscular mycorrhizal fungi (AMF) are able to associate with plant roots and affect the ability of different species to absorb water and nutrients from the soil, promoting changes in plant growth. Other groups may promote positive or negative changes in plant...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Agriculture; Mycorrhizal fungi; PGPR; Ecology.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582014000400022

Sourgrass densities affecting the initial growth and macronutrient content of coffee plants
Provedor de dados: 87
Autores: Carvalho,L.B; Alves,P.L.C.A; Bianco,S.
The objective of this work was to evaluate the coexistence effects of coffee (Coffea arabica) with densities of sourgrass (Digitaria insularis) on crop macronutrient content and plant growth. The experiment was conducted in plots where one coffee plant was maintained in coexistence with 0 (weed-free check), 1, 2, 4, 8, and 16 sourgrass plants, using a completely randomized design with three replicates. Reduction of coffee growth and macronutrient content, except P that increased, started when the coexistence occurred with sourgrass plants in a density of 1 plant per plot. In general, macronutrient content was reduced by 18-50%, while growth characteristics were reduced by 9-41%, when coffee plants coexisted with 16 plants of sourgrass. Thus, sourgrass...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Coffea arabica; Digitaria insularis; Competition; Additive experiment; Nutrients.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000100012

EFFECTS OF PLANTING DATE AND SPATIAL ARRANGEMENT ON COMMON BEAN (Phaseolus vulgaris) YIELD UNDER WEED-FREE AND WEEDY CONDITIONS
Provedor de dados: 87
Autores: ESMAEILZADEH,S.; AMINPANAH,H.
ABSTRACTTo evaluate the effect of planting date and spatial pattern on common bean yield under weed-free and weed-infested conditions, an experiment was conducted in Kelachay, Northern Iran, in 2013. The experimental design was a randomized complete block in a factorial arrangement with three replicates. Factors were planting date (10 August and 20 August), spatial pattern (square and rectangular planting pattern, with a planting distance of 30 x 30 cm and 45 x 20 cm, respectively), and weed management regime (weed-free and weedy conditions, weeded and not weeded throughout the growing season, respectively). Results showed that the main effect of planting date was significant only for pod number per plant and seed number per pod. At the same time, pod...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Common bean; Competition; Planting date; Planting pattern; Phaseolus vulgaris.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582015000300425

Influence of Weeds on Yacon Initial Growth and Development
Provedor de dados: 87
Autores: CABRAL,M.O.; OLIVEIRA,F.L.; DALVI,L.P.; TEIXEIRA,A.G.; ROCHA,L.J.F.N.; PEDROSA,J.L.F.
ABSTRACT: The consumption of yacon has been increasing around the world due to the nutritional and pharmaceutical properties of this plant. The growing commercial interest in yacon (Smallanthus sonchifolius) generates a demand for crop management research studies, including the effect of weed competition on yacon, which was not yet studied. Thus, this study was performed with the objective of evaluating the effects of weed competition on yacon development and growth. The experimental design was completely randomized with four treatments and seven replicates. Treatments were yacon with the interference of four weed species: Cyperus rotundus L. (nutgrass), Commelina benghalensis L. (tropical spiderwort), Amaranthus viridis L. (slender amaranth) and Bidens...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Smallanthus sonchifolius; Commelina benghalensis; Amaranthus viridis; Cyperus rotundus; Bidens pilosa; Competition.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100220

Does the Interference of GR® Volunteer Corn Alters Stress Metabolism on Soybean?
Provedor de dados: 87
Autores: PIASECKI,C.; RIZZARDI,M.A.; SCHONS,J.; CAVERZAN,A.; CHAVARRIA,G.
ABSTRACT: The cultivation of GR® corn prior to soybean favors the occurrence of GR® volunteer corn plants interfering in soybean crops. The interference of volunteer corn causes the soybean yield losses, and the magnitude of losses varies with the corn density. The soybean yield losses can be partially explained by the occurrence of oxidative stress, which occurs by the higher content of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2). The objective of this study was to quantify H2O2 content and the activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) on soybean as a function of interference of populations of GR® volunteer corn originated from individual plants and clumps (clumps are seven corn plants...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Glycine max; Zea mays; Volunteer plants; Competition; Oxidative stress.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100219

Initial growth and competitive ability of yellow nutsedge and irrigated rice
Provedor de dados: 87
Autores: Westendorff,N.R.; Agostinetto,D.; Ulguim,A.R.; Langaro,A.C.; Thürmer,L.
Weeds cause significant reduction in the irrigated rice crop yield. Cyperus esculentus (yellow nutsedge) is adapted to irrigate environment. Information on the competitive ability of the weed to the culture, and their environmental adaptation, are scarce. In this study, we sought to determine the initial growth and competitive ability of yellow nutsedge and irrigated rice, as a function of cultivar growth cycle. Initial growth and competition studies were conducted in a randomized complete design in a greenhouse in the agricultural year 2010/11. For the initial growth study, the treatments consisted of a factorial combination of a biotype of yellow nutsedge and two rice cultivars in the function of the vegetative cycle (BRS Querência: early cycle - IRGA...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Cyperus esculentus; Oryza sativa; Competition; Fitness.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000400007

Effect of weed interference on soybean cultivars at two sowing times
Provedor de dados: 87
Autores: Marangoni,R.E.; Jakelaitis,A.; Tavares,C.J.; Rezende,B.P.M.; Mello Filho,O.L.; Cunha,P.C.R.
This study aimed to evaluate the effects of weed interference on soybean cultivars at two sowing times in Urutaí, GO. The treatments were arranged in split-plots, and the sowing times (November 16 and December 16, 2009) were allocated in the plots; the soybean cultivars [BRSGO Amaralina, P98C81 (semi-late cycle) BRSGO Raissa, BRSGO Indiara, P98Y11 (median cycle) and BRSGO 7560, BRSGO Caiapônia, Emgopa 302RR (early cycle)] were allocated in the split-plots; and the coexistence or non coexistence of soybean cultivars with weeds, throughout their cycle, was allocated in the split-plots. Non coexistence was established by manual weeding. The experiment was arranged in randomized blocks with four replications. It was verified that the optimal time for sowing...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Glycine max; Competition; Crop yield.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000300003

Interference Periods of Raphanus raphanistrum L. in Sunflower Crop
Provedor de dados: 87
Autores: AGOSTINETTO,D.; WESTENDORFF,N.; ZANDONÁ,R.R.; ULGUIM,A.R.; LANGARO,A.C.
ABSTRACT: Raphanus raphanistrum L. (wild radish) stands out among the weeds that cause greatest damage to the sunflower crop, due to the development cycle and adaptability. The objective of this research was to determine interference periods of sunflower interacting with wild radish, and the effects of competition on yield and its components. The experiment was conducted in the field in a randomized block design with four replications. The treatments were arranged in a factorial design with factor A composed of wild radish coexistence or control in sunflower, and factor B, for eight periods (0, 7, 14, 21, 28, 35, 42 and 135 days after crop emergence). It was evaluated height, diameter of chapters, achene yield and dry matter of weeds and crop. The presence...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Helianthus annuus; Competition; Weeds.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100240

Effect of plant density and seed position on mother plant on physiological characteristic of cocklebur (Xanthium strumarium) seeds
Provedor de dados: 87
Autores: Foroughi,A.; Gherekhloo,J.; Ghaderi-Far,F.
Experiments were conducted in 2010 to determine the influence of plant density and seed position on the mother plant on seed physiological characteristics of cocklebur (Xanthium strumarium). Cocklebur burs were collected in fall of 2010 from Research Farm of University of Agricultural Sciences and Natural Resources of Gorgan, Iran. The experiment was established as factorial arrangement using a completely randomized design with three replications. The factors included different densities of cocklebur (0, 2, 4, 6 and 8 plant m-2) and the top and bottom parts of the canopy. Non dormant seeds were used for determining cardinal temperatures and tolerance to salinity and drought stresses. Base, optimum and ceiling germination temperatures were estimated between...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Shade environment; Cardinal temperature; Competition; Dormancy.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582014000100007

Assessing the Competitive Ability of Rhynchosia capitata; an Emerging Summer Weed in Asia
Provedor de dados: 87
Autores: Ali,H.H.; Tanveer,A.; Naeem,M.; Jamil,M.; Iqbal,M.; Chadhar,A.R.; Kashif,M.S.
Rhynchosia capitata is a newly emerging threatening weed of summer crops in many Asian countries. We conducted 2-yr experiments to evaluate R. capitata competition with mungbean under irrigated conditions. Rhynchosia capitata was allowed to compete with mungbean for 0, 3, 4, 5, 6, 7 weeks after planting and for full crop season. The competitive ability of R. capitata was assessed by measuring its dry weight, micro and macro nutrient contents and uptake; and its effects on mungbean growth and yield parameters. The results showed that full season weed competition produced highest dry weight of R. capitata and its macro and micronutrient contents and uptake. Yield and yield components of mungbean decreased in a linear fashion with increase in competition...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Rhynchosia capitata; Emerging; Infestation; Competition; Mungbean; Nutrients.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582015000200175

Interference Periods of Weeds in Maize in No-Tillage and Conventional Systems at High Altitudes
Provedor de dados: 87
Autores: HELVIG,E.O.; PINHEIRO,K.K.G.; DRANCA,A.C.; SILVA,A.A.P.; MENDES,M.C.; MACIEL,C.D.G.
ABSTRACT: The objective of this study was to determine the coexistence periods of weeds (CTWR = critical timing of weed removal) and control (CWFP = critical weed-free period) in maize crops in no-tillage and conventional systems at high altitudes in southern Brazil. To this end, four experiments were conducted in Guarapuava-Paraná during the 2016/2017 crop season using P2530™ (conventional) and P3271H™ (transgenic genetically modified for glyphosate tolerance) hybrids in no-tillage and conventional systems with crop residues of black oat (Avena strigosa). The experimental design was a randomized complete block with five repetitions. The treatments were divided into periods of CTWR and CWFP for 0, 7, 14, 28, 42, 63, and 126 days after the emergence of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Zea mays L.; Competition; Control; Productivity.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100229

Redroot pigweed interference with lettuce crop
Provedor de dados: 87
Autores: Casadei,Eloisa; L. Bacha,Allan; S. Rodrigues,Juliana; S. Santos,Renata T.; L.C.A. Alves,Pedro; B.C. Filho,Arthur.
Abstract  Background:  Lettuce-production areas in Brazil are frequently infested by pigweed plants, which can interfere with production by competing for resources or releasing allelopathic compounds in the environment.  Objective:  The present study evaluated the effect of redroot pigweed (Amaranthus retroflexus) density and distribution on lettuce crop (Lactuca sativa L.).  Methods:  The cultivars Lídia, Verônica, Lucy Brown and Salad Bowl were used. After transplanting, these plants coexisted until harvest with four pigweed plants (equivalent to 16 plants m-2) located within or outside planting rows, or with one pigweed plant located at the center of the plot (4 plants m-2), as well as a control without weed. The experiment was conducted in an open and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lactuca sativa L.; Amaranthus retroflexus; Competition; Weeds; Density; Distribution.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100308

Management of Bidens pilosa and Commelina benghalensis in organic corn cultivation under no-tillage
Provedor de dados: 87
Autores: Lemos,J.P.; Galvão,J.C.C.; Silva,A.A.; Fontanetti,A.; Cecon,P.R.; Lemos,L.M.C.
Mowing is one of the most important methods used to control weeds in organic farming, under the no-tillage system. This study aimed to evaluate the effects of three weed management techniques on weed development, using the weeds Bidens pilosa and Commelina benghalensis, in competition with organic corn {mowing at the three-leaf stage (14 days after corn emergence - DACE), mowing at the three- and six-leaf stage (14 and 25 DACE), and no mowing. Single cultivation with no mowing was also evaluated for these weeds. Mowings performed at 14 and 25 DACE prevented the production of B. pilosa seeds, ensuring efficient control of this species. However, the use of this technique was shown to be inefficient in the control of C. benghalensis.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Mowings; Regrowth; Morphology; Competition.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000200012

Phytosociology of Weeds in Cultivation of Two Varieties of Cassava1
Provedor de dados: 87
Autores: MILÉO,L.J.; SILVA,J.F.; ALBERTINO,S.M.F.; LEITE,B.N.; MENEZES,D.S.; SANTOS,A.F.
ABSTRACT This study has aimed to carry out a phytosociological survey of weeds in different collection periods, in cassava crops of two varieties grown in two consecutive years. The varieties were Pão, of the sweet class, and Racha-terra, of the bitter class. The weeds surveys were performed at 28, 56, 84, 112, 140, 168, 196, 224, 252, 280 and 308 days after planting in the experimental units of each variety. For weeds sampling, a sampler with an area of 0.25 m2 released twice at random in the floor area of the treatments was used. The phytosociological survey quantified 5,708 individuals distributed in 17 families, represented by 32 species, of which 25 were dicotyledonous and seven were monocotyledonous. The most representative families in number of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Tillage; Manihot esculenta.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000200267

Weed Interference Periods and Transplanting Densities of Onion Crop in the Brazilian Region of Guarapuava, PR1
Provedor de dados: 87
Autores: SOUZA,J.I.; SILVA,A.A.P.; CHAGAS,R.R.; OLIVEIRA NETO,A.M.; MACIEL,C.D.G.; RESENDE,J.T.V.; ONO,E.O.
ABSTRACT The study was conducted with the objective of determining the critical periods of interference prevention (CPIP) and the best period for the management of weeds community in onion crop Crioula Mercosul genotype, transplanted in distinct plants densities. The experiment was carried out in field conditions in the Brazilian municipality of Guarapuava, Paraná State, during the 2012 and 2013 agricultural years, at Universidade Estadual do Centro-Oeste - UNICENTRO. Treatments were disposed in randomized complete blocks and experimental design, with five repetitions, consisting of weeds coexistence periods and weeds control at 14, 28, 56, 112 and 168 days after transplanting the seedlings (DATS), using 0.6, 0.8 and 1.0 million plants ha-1. Weeds...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Allium cepa; Competition; Plant arrangement; Bulb yield.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000200299

Population Interference of Glyphosate Resistant and Susceptible Ryegrass on Eucalyptus Initial Development
Provedor de dados: 87
Autores: BRAGA,A.F.; BARROSO,A.A.M.; AMARAL,C.L.; NEPOMUCENO,M.P.; ALVES,P.L.C.A.
ABSTRACT: The repetitive use of herbicides with the same mechanism of action causes the selection of resistant weeds, such as ryegrass. Considering the occurrence of ryegrass (Lolium multiflorum) in eucalyptus, a crop on which glyphosate is used, it is necessary to study its interference. The objective of this study was to evaluate the effect of densities (0, 10, 20, 30 and 50 plants m-2) of two ryegrass biotypes (resistant and susceptible to glyphosate) on seedlings of two eucalyptus clones (I-144 and 1407). The used experimental design was in randomized blocks with four replications, following a 2 x 5 factorial arrangement for each clone. The height and diameter of the clones were evaluated at 0, 14, 28, 42, 56 and 70 days after transplantation (DAT),...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lolium multiflorum; Eucalyptus urograndis; Competition.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100286

Interference of GR® Volunteer Corn Population and Origin on Soybean Grain Yield Losses
Provedor de dados: 87
Autores: PIASECKI,C.; RIZZARDI,M.A.; SCHWADE,D.P.; TRES,M.; SARTORI,J.
ABSTRACT: The cultivation of GR® maize prior to soybean, mainly in the no-tillage system favors the higher occurrence of GR® volunteer corn interfering in soybean crops. Volunteer corn originate from seeds that were lost during harvest or from non-harvested seeds from the field; these are individual seeds, originating individual plants, or several seeds adhered to segments of the rachis, which originate clumps. Volunteer corn in the form of clumps predominates in soybean crops, but little information about its effect on soybean is available in the literature. During two years, three experiments were carried out with the objective of evaluate the impact of the interference of GR® F2 generation volunteer corn populations coming from individual and clump...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Glycine max; Zea mays; Competition; Individual plants; Clumps; Harvest losses.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100206

Intercropping Between Corn and Urochloa brizantha Managed with Mesotrione Underdoses
Provedor de dados: 87
Autores: MARTINS,D.A.; JAKELAITIS,A.; PEREIRA,L.S.; MOURA,L.M.F.; GUIMARÃES,K.C.
ABSTRACT: Corn and forage intercropping system has been commonly used for pasture establishment or renewal. In addition, the use of reduced doses of herbicides selective to corn has facilitated coexistence by reducing competitiveness against forage species. This study aimed to evaluate the effects of mesotrione underdoses in a corn and Urochloa brizantha intercropping on weed population dynamics, corn yield, and forage performance and nutritional quality. For this purpose, five mesotrione doses were tested (0.0, 9.6, 19.2, 38.4, and 57.6 g ha-1) in corn and forage intercropping and monocultures. Individual density and weed dry matter were influenced by mesotrione doses, intercropping, and precipitation distribution over the evaluated period in the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Zea mays L.; Competition; Herbicide; Crop-livestock integration; Weeds.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582019000100255

INTERFERENCE PERIODS AMONG WEEDS AND SOYBEAN RR TM CROPS IN THE WESTERN CENTER AREA OF THE BRAZILIAN STATE OF PARANÁ
Provedor de dados: 87
Autores: SILVA,A.A.P.; OLIVEIRA NETO,A.M.; GUERRA,N.; HELVIG,E.O.; MACIEL,C.D.G.
ABSTRACT One of the factors that can influence soybeans yield is the interference imposed by weeds. This research has aimed to determine the critical period of weed interference on cv. INT 6100 RRTM soybeans. The experiment was conducted under field conditions at Campo Mourão County, Parana State, in the 2013/2014 harvest, using randomized blocks, arranged in a 2 x 8 factorial, with four replications. In the first factor, the coexistence (period before weed interference) and control (total period of weed interference prevention) periods were assessed. The second factor consisted of management times of weed species (0, 7, 14, 28, 35, 49, 56 and 130 days after emergence - DAE). The evaluations performed were density and shoot dry matter of the weed...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Coexistence; Weed control; Competition; Glycine max.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582015000400707

Periods of Weed Interference on Orange Tree Crops
Provedor de dados: 87
Autores: GONÇALVES,G.S.; CARVALHO,J.E.B.; GARCIA,M.V.B.; GAMA,L.A.; AZEVEDO,C.L.L.L.; SILVA,J.F.
ABSTRACT: Current orange tree cultivation practices in the Brazilian State of Amazonas present several production problems, being the inadequate weed management the most important one, and significantly affecting fruit productivity. However, if weeds are managed properly, their coexistence with orange cultivars does not affect the fruit yield of orange trees. Thus, the objective of this research was to identify the period of longer weed interference in orange production. The treatments were conducted during the 2013 and 2014 harvests as follows: one control treatment with no coexistence of weeds and crop throughout the growing season; and six periods of coexistence (October to January, February to May, June to September, October to May, October to January,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Citrus sinensis; Fruit yield; Competition.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100280

Implications of weeds of genus euphorbia for crop production: a review
Provedor de dados: 87
Autores: Tanveer,A.; Khaliq,A.; Javaid,M.M.; Chaudhry,M.N.; Awan,I.
The genus Euphorbia comprises about 2000 species ranging from annuals to trees, including C3, C4, and CAM species. Euphorbia species widely studied in agriculture includes E. antiquorum, E. carollata, E. dentata, E. dracunculoides, E. esula, E. geniculata, E. granulata, E. helioscopia, E. heterophylla, E. hierosolymitana, E. hirta, E. maculata, E. microphylla, E. nerifolia, E. piluifera, E. pulcherrima, E. royleana, E. supine, and E. thiamifolia. These species have been reported mainly in field crops/vegetables, orchards, pastures, and rangelands. Euphorbia plants may present allelopathic effect over desirable cereals, pulses, oilseeds, vegetables, forage plants, and nitrifying bacteria, posing a serious threat to livestock production on open range lands...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Allelopathy; Crops; Pastures; Livestock; Plant protection.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582013000300024

Antidumping and Market Power in the Agriculture Sector, with a Special Case Study of the Fresh Tomato Industry
Provedor de dados: 31
Autores: Baylis,   Katherine R.
In this article we highlight the anticompetitive nature of antidumping (AD) legislation. Antidumping legislation was set up to protect domestic firms from predatory pricing by foreign firms. We argue that protecting highly concentrated industries drastically reduces competition at home. In cases where the industry consists only of one or two firms, import restriction may breed monopolies at the expense of domestic consumers. This article looks at cases filed by the agriculture sector, and at the market concentration of industries in this sector, to illustrate the above possibility. We study the case of fresh tomatoes in detail to further demonstrate the anticompetitive nature of AD legislation. We show the effect of AD legislation on imports, as well as...
Tipo: Journal Article
Palavras-chave: Agriculture; Antidumping legislation; Competition; Fresh tomato industry; Crop Production/Industries; International Relations/Trade.
Ano: 2008
URL: http://purl.umn.edu/6320

Analogous Products and Food Quality Products: Two Poles of the Competition
Provedor de dados: 31
Autores: Bošková,   Iveta.
The globalisation of processing industry and the consolidation of the international retail trade, together with the increase of imports after the EU access, supported the competition hot up and saturation of domestic food market.  Both food processors and food retailers are exposed to increasing competition. In order to maintenance on the market they are increasingly pressed to minimize their costs and/or to accomplish higher prices for products with competitive advantage. Besides of that all participants of the agri-food chain are pressed to intensify marketing support of their goods.  Aiming to reduce the costs, some of processors choose the way by the substitution of part of the input material by another, cheaper one. On the other hand, the offer of...
Tipo: Conference Paper or Presentation
Palavras-chave: Competition; Marketing; Quality; Food Consumption/Nutrition/Food Safety; Marketing.
Ano: 2007
URL: http://purl.umn.edu/7880

How Rising Competition Among Microfinance Lenders Affects Incumbent Village Banks
Provedor de dados: 31
Autores: McIntosh,   Craig; de Janvry,   Alain; Sadoulet,   Elisabeth.
This paper uses data from Uganda's largest incumbent microfinance institution to analyze the impact of entry by competing lenders on client behavior. We first examine the geographic placement decisions of competitors, and find that placement decisions are strongly affected by district-level characteristics. We observe that increased competition induces a decline in repayment performance and in savings deposited with the incumbent Village Bank, suggesting multiple loan-taking by clients. Urban clients take multiple loans primarily from lenders with more individual methodologies, while rural clients borrow from several group lenders. Individuals who operate larger businesses are the ones most likely to leave the incumbent Village Bank when a Solidarity Group...
Tipo: Working or Discussion Paper
Palavras-chave: Microfinance; Competition; Credit markets; Financial Economics; O16; D14; L1.
Ano: 2003
URL: http://purl.umn.edu/25073

Measuring Competition for Textiles: Does the United States Make the Grade?
Provedor de dados: 31
Autores: Welch,   J. Mark; Lyford,   Conrad P.
Increasing competition from foreign manufacturers threatens the viability of textile producers in the United States. This paper evaluates the U.S. competitive position in the cotton yarn segment using established quantifiable measures and provides an overall competitive assessment. The measures employed show the United States to be at a relative competitive disadvantage when compared to major international producers of cotton yarn. However, the margin of this competitive disadvantage is shown to be relatively small and in some cases, decreasing.
Tipo: Journal Article
Palavras-chave: Competition; Cotton; International trade; Textiles; Agribusiness; Agricultural and Food Policy; Crop Production/Industries; Demand and Price Analysis; International Relations/Trade.
Ano: 2007
URL: http://purl.umn.edu/44901

Fish Chain Performance in Madrid Market: An Empirical Analysis
Provedor de dados: 31
Autores: de Felipe,   Isabel; Briz,   Julian.
Food chain analysis is becoming a useful instrument to increase efficiency. We focus the attention in the fish sector looking at the links from consumer to wholesalers in the region of Madrid. In order to get adequate information we developed face to face enquiries to the consumers, retailers and wholesalers. The analysis of the Madrid market give us a useful approach of the national and international sector, due to the fact that Mercamadrid is the biggest fish wholesale market in Europe, and the consumption in Madrid is representative in many ways of the Spanish market. Finally there are some conclusions and recommendations oriented toward the stakeholders.
Tipo: Conference Paper or Presentation
Palavras-chave: Fish; Food chain; Performance; Competition; Agribusiness.
Ano: 2004
URL: http://purl.umn.edu/24987

Restructuring and the Cost of Reducing NOx Emissions in Electricity Generation
Provedor de dados: 31
Autores: Palmer,   Karen L.; Burtraw,   Dallas; Bharvirkar,   Ranjit; Paul,   Anthony.
We look at the effects of restructuring on three issues: (a) economic surplus and environmental quality, (b) the cost of NOx control policies and who bears the costs, and (c) the cost-effectiveness of a seasonal and an annual NOx cap in the SIP Call region. We find that without the NOx cap, nationwide restructuring leads to higher NOx and carbon emissions from the electricity sector. Adding either a seasonal or an annual NOx cap-and-trade regime in the eastern United States mitigates the increase in NOx emissions but has a much smaller effect on carbon emissions. The out-of-pocket compliance cost associated with achieving a seasonal or an annual NOx cap is moderately higher with nationwide restructuring than without, but the changes in economic surplus are...
Tipo: Working or Discussion Paper
Palavras-chave: Electricity; Restructuring; Deregulation; Competition; Emissions trading; Particulates; Nitrogen oxides; NOx; Health benefits; Cost effectiveness; Environmental Economics and Policy; Q2; Q4.
Ano: 2001
URL: http://purl.umn.edu/10549

Empirical Analysis of Competitive Interaction in Food Product Categories
Provedor de dados: 31
Autores: Putsis,   William P., Jr.
This paper provides an overview of recent research on estimating competitive interaction in food product categories. In particular, the focus of this review is on research using scanner data conducted at the disaggregate (e.g., store, chain or local market) level, including empirical studies of vertical (i.e., within-channel) conduct. Studies addressing the competitive interaction on price, as well as non-price variables (e.g., in-store display and feature advertising) are considered. The author first describes the methodologies available for measuring the competitive interaction between firms and then briefly summarizes recent empirical developments. Given the complexity of the interactions that take place in practice, it is argued that much of the...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Competitive strategy; Channel behavior; Agribusiness; Demand and Price Analysis; Industrial Organization.
Ano: 1998
URL: http://purl.umn.edu/25221

Product Quality in the Food Chain: Do Cooperatives Offer High Quality Products?
Provedor de dados: 31
Autores: Pennerstorfer,   Dieter; Weiss,   Christoph R.
Cooperatives and investor-owned firms are alternative forms of business organisation that coexist and compete in many markets. The theoretical literature has identified a number of comparative advantages and disadvantages of cooperatives. Decentralized decision making within cooperatives may lead to quality coordination problems (free-riding on product quality), for example: whereas the individual member has to bear the full costs associated with higher quality, the benefits of delivering higher quality will be shared among all members. The present paper investigates this free-riding problem in determining product quality within a marketing cooperative in a vertically related market (food chain). On the basis of a mixed-oligopoly model, we show that the...
Tipo: Conference Paper or Presentation
Palavras-chave: Product quality; Cooperatives; Food chain; Competition; Agricultural and Food Policy; Food Consumption/Nutrition/Food Safety.
Ano: 2009
URL: http://purl.umn.edu/58111

Assessing Competition in the U.S. Beef Packing Industry
Provedor de dados: 31
Autores: Ward,   Clement E.
Tipo: Journal Article
Palavras-chave: Beef; Cattle; Competition; Concentration; Market structure; Meatpacking; Pricing; Agribusiness; Livestock Production/Industries; L13; Q13.
Ano: 2010
URL: http://purl.umn.edu/94758

Common Labels and Market Mechanisms
Provedor de dados: 31
Autores: Boizot-Szantai,   Christine; Lecocq,   Sebastien; Marette,   Stephan.
In this article, the impact of common labels is investigated with both theoretical and empirical approaches. Recent statistics regarding the egg market in France suggest that retailer brands largely adopt common labels. A simple theoretical framework enables us to determine the conditions under which producers and/or retailers with different product qualities decide to post a common label on their products. In particular, a situation of multiple equilibria (one where the label is used by the high-quality seller only and one where it is used by the low-quality seller only) is exhibited when the cost of the label is relatively large. The demand is then estimated for different segments of the French egg market, including producer/retailer brands with/without...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Demand estimation; Labels; Product differentiation; Marketing.
Ano: 2005
URL: http://purl.umn.edu/18588

U.S. FRESH PRODUCE MARKETS:  MARKETING CHANNELS, TRADE PRACTICES, AND RETAIL PRICING BEHAVIOR
Provedor de dados: 31
Autores: Dimitri,   Carolyn; Tegene,   Abebayehu; Kaufman,   Phillip R.
Retail consolidation, technological change in production and marketing, and growing consumer demand for produce have altered the traditional market relationships between producers, wholesalers, and retailers. Increasingly, produce suppliers are asked to provide additional marketing services and incentives in exchange for volume purchases and other commitments by buyers. This report synthesizes the results from a multiphase project that examined the dynamics of produce marketing, the produce shipper-retailer relationship, and how changes in the produce market affect the relative market influence of producers, retailers, and consumers.
Tipo: Working or Discussion Paper
Palavras-chave: Fresh fruits and vegetables; Fresh produce; Fresh produce marketing channels; Supermarket; Market power; Competition; Trading practices; Crop Production/Industries; Industrial Organization.
Ano: 2003
URL: http://purl.umn.edu/33907

The Environmental Impacts of Electricity Restructuring: Looking Back and Looking Forward
Provedor de dados: 31
Autores: Palmer,   Karen L.; Burtraw,   Dallas.
In the mid-1990s, when the Federal Energy Regulatory Commission was preparing to release Order 888 requiring open access to the transmission grid, the commission, environmental groups, and the Environmental Protection Agency, among others, raised the question of how open access and greater competition in wholesale electricity markets might affect the environment. If open access worked as expected, underutilized older coal-fired generators in the Midwest and elsewhere might find new markets for their power, leading to associated increases in air pollution emissions. Restructuring also might lead to retirements of inefficient nuclear facilities, whose generation would be replaced by fossil generation, further increasing emissions. On the other hand, some...
Tipo: Working or Discussion Paper
Palavras-chave: Electricity; Electric utilities; Regulation; Competition; Environment; Air pollution; Natural gas; Coal; Nuclear; Renewables; Customer choice; Resource /Energy Economics and Policy; L51; L94; L98.
Ano: 2005
URL: http://purl.umn.edu/10656

HOW COMPETITIVE IS THE WORLD WHEAT MARKET?
Provedor de dados: 31
Autores: Carter,   Colin A.; MacLaren,   Donald; Yilmaz,   Alper.
Japan is one of the largest importers of wheat in the world, with imports originating from three countries, Australia, Canada, and the United States.  Australia, Canada, and Japan all use a government single-desk agency to control wheat trade.  Many previous studies on competition in the world grain trade have argued the market is imperfectly competitive, and they often point to the Japanese market. We study the Japanese wheat import market for this reason, but find no compelling evidence of imperfect competition.
Tipo: Working or Discussion Paper
Palavras-chave: Wheat trade; Competition; Crop Production/Industries; International Relations/Trade; F14; L10; Q17.
Ano: 1999
URL: http://purl.umn.edu/11973

Reworking the Standard Model of Competitive Markets: The Role of Fuzzy Logic and Genetic Algorithms in Modelling Complex Non-Linear Economic System
Provedor de dados: 31
Autores: Smith,   Peter.
Some aspects of economic systems (eg, nonlinearity, qualitative variables) are intractable when incorporated into models. The widespread practice of excluding them (or greatly limiting their role) produces deviations of unknown size and form between the resulting models and the reality they purport to represent. To explore this issue, and the extent to which a change in methodology can improve tractability, a combination of two techniques, fuzzy logic and genetic algorithms, was applied to the problem of how the sellers in a freely competitive market, if initially trading at different prices, can find their way to supply/demand equilibrium. A multi-agent model was used to simulate the evolution of autonomously- learnt rule-governed behaviour, (i), under...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Markets; Walrasian Crier; Equilibrium; Fuzzy logic; Genetic algorithms; Evolutionary algorithms; Industrial Organization.
Ano: 2004
URL: http://purl.umn.edu/30569

Patents, Spillovers, and Competition in Biotechnology
Provedor de dados: 31
Autores: Austin,   David H.
I perform an event study on 600+ patents awarded primarily to 20 leading biotechnology firms and find significant changes in market values at the time of the awards. Adjusting for partial anticipation of events, I estimate that core technology patents in highly contested research areas are expected to generate between $13 and $21 million of economic value. They also generate spillover benefits for the patentee's rivals-presumably including knowledge transfers-valued at $3 to $6 million per firm. Awardees may appropriate only half of private benefits, although I observe negative spillovers for some high-profile awards. Most patents have no significant market impact.
Tipo: Working or Discussion Paper
Palavras-chave: Innovation; Patent value; Spillover; Competition; Event study; Research and Development/Tech Change/Emerging Technologies; G14; O31; O34; L65.
Ano: 2000
URL: http://purl.umn.edu/10808

THE PROVISION OF RAIL SERVICE: THE IMPACT OF COMPETITION
Provedor de dados: 31
Autores: Fulton,   Murray E.; Gray,   Richard S.
Grain transportation is one of the most important economic issues for grain producers in the Northern Plains. The reliance on export markets and the long distances to port position means that transportation costs have a significant effect on the price received by farmers.  In the prairie region of Canada, rail transportation is undergoing a major transformation that will affect the competitive positions of agriculture in both the United States and Canada and influence the direction of grain flows between the two countries. Rail rates are no longer legislated although a cap is still in place), restrictions on branch line abandonment have been lifted, and further deregulation of price and car allocation is being considered. Some parties, including the...
Tipo: Working or Discussion Paper
Palavras-chave: Barriers to entry; Competition; Grain handling; Grain transportation; Monopoly; Railroads; Regulation; Public Economics; K2; L1; L9; L5.
Ano: 1998
URL: http://purl.umn.edu/29164

Rural Health Insurance and Competitive Markets: Not Always Compatible?
Provedor de dados: 31
Autores: Mueller,   Keith J.
Tipo: Journal Article
Palavras-chave: Health Insurance; Rural Health; Health Markets; Competition; Health Policy; Health Economics and Policy.
Ano: 2009
URL: http://purl.umn.edu/93836

The power of two: squaring off with Australia’s large supermarket chains
Provedor de dados: 31
Autores: Round,   David K.
The level and nature of competition in supermarket retailing in Australia has been hotly debated as a policy issue in recent times. The creeping acquisitions of smaller groups by Coles and Woolworths have led to several investigations amid claims that consumers will be disadvantaged by the growth of the two big chains. Yet little convincing evidence has been found to support these assertions. Although on occasions the big two may have used their power vertically to squeeze suppliers, consumers have experienced highly competitive retail markets. In this paper, it is argued that it is market conduct, not structure, that should be the prime focus of regulatory and policy interest, and that recent corporate activity may lead to a third force in supermarket...
Tipo: Journal Article
Palavras-chave: Competition; Market power; Mergers and acquisitions; Supermarkets; Agribusiness.
Ano: 2006
URL: http://purl.umn.edu/116860

Gender Differences in Output Quality and Quantity under Competition and Time Constraints: Evidence from a Pilot Study
Provedor de dados: 31
Autores: Shurchkov,   Olga.
Gender gaps in income and level of position in the workplace are widespread. One explanation for this inequality is that the genders perform differently under competitive conditions, as previous experimental studies have found a significant gender gap in competitive tasks that are perceived to favor men. In this paper, we use a verbal task that is perceived to favor women and find no gender difference under competition per se. We also reject the hypothesis that a .stereotype threat. explains the inability of women to improve performance under competition. We propose an alternative explanation for gender inequality: namely, that women and men respond differently to time pressure. With reduced time pressure, competition in verbal tasks greatly increases the...
Tipo: Working or Discussion Paper
Palavras-chave: Gender Differences; Competition; Effects of Time Pressure; Labor and Human Capital; C9; J16; J71.
Ano: 2009
URL: http://purl.umn.edu/55294

A Life-Cycle Perspective on Governing Cooperative Enterprises in Agriculture
Provedor de dados: 31
Autores: Hueth,   Brent; Reynolds,   Anne.
Tipo: Journal Article
Palavras-chave: Cooperatives; Governance; Life Cycle; Competition; Finance; Agribusiness; Q12; Q13; Q14.
Ano: 2011
URL: http://purl.umn.edu/117411

Fish farming in competition with an open-access fishery
Provedor de dados: 31
Autores: Berck,   Peter; Perloff,   Jeffrey M.
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Economic aspects; Equilibrium (economics); Fish-culture; Fisheries; Supply and demand.
Ano: 1984
URL: http://purl.umn.edu/43308

The effect of competition between two spatially separated markets - An investigation of two interlinked Bak-Sneppen models
Provedor de dados: 31
Autores: Damgaard,   Martin.
This paper investigates the effect of competition in a market consisting of interlinked economic agents. In particular, the effect of increased competition from the surrounding markets is demonstrated. The presented work is an extension of the Bak-Sneppen model (Bak and Sneppen 1993). Here are two Bak-Sneppen models interlinked such that if the lowest fitness value of one market exceeds the fitness values of the other market minus transportation cost, all cells lower than this band will receive a new random value. The model shows that interdependency between markets has a strong effect on the competitiveness of the least competitive market. The external competition is able to make the least competitive market perform better as well as worse than on its own.
Tipo: Conference Paper or Presentation
Palavras-chave: Bak-Sneppen model; Interdependency; Competition; Marketing.
Ano: 2008
URL: http://purl.umn.edu/44056

Food Procurement by USDA's Farm Service Agency
Provedor de dados: 31
Autores: MacDonald,   James M.; Handy,   Charles R.; Plato,   Gerald E.
USDA's Farm Service Agency (FSA) purchases food products for distribution through several of the Department's food assistance programs. This report describes FSA purchase methods and compares them to procurement strategies used by other Federal agencies and by private sector firms. It summarizes the principal policy issues faced by FSA in designing procurement strategies. And it uses a detailed statistical analysis to compare FSA prices to those realized in the private sector, and to identify the separate effects of agricultural commodity prices, seasonality, client location, purchase volumes, product characteristics, and competition on FSA product prices.
Tipo: Report
Palavras-chave: Procurement; Auctions; Food assistance; Competition; Food Consumption/Nutrition/Food Safety.
Ano: 1998
URL: http://purl.umn.edu/33925

WACHSTUMSDYNAMIK GENOSSENSCHAFTLICHER GRUPPEN- Eine okonomische Analyse genossenschaftlicher Gruppengrosse und Genossenschafts...
Provedor de dados: 31
Autores: Lasowski,   Ophir; Kuhl,   Rainer.
Cooperatives are not only a legal form, but also a form of organisation, which is owned by a group of individuals. For gaining and sustaining competitiveness cooperatives are forced to grow into certain minimum optimal size categories. Common measures of size are turnover or total assets. But, for cooperatives the number of members has been a quite popular measure for cooperatives' success, size, and their attractiveness. Although often mentioned, the number of members has only been taken as a given value, ignoring the influence of the group itself on its own size. However, there has been no attempt to measure the potential size of a group and its growth dynamic under a given set-up. With the development of a strategic decision game for a hypothetical...
Tipo: Conference Paper or Presentation
Palavras-chave: Cooperatives; Growth Dynamic; Group-Size; Competition; Member-Value; Strategic Game; Agribusiness.
Ano: 2006
URL: http://purl.umn.edu/14974

The market analysis of branded, new generation hungaricums
Provedor de dados: 31
Autores: Szakaly,   Zoltan; Szigeti,   Orsolya; Berke,   Sz.; Szente,   Viktoria.
Natural capabilities of Hungary are particularly favourable for agricultural and food production. There are good possibilities both in cultivation of plants and in animal husbandry on plough- and grasslands. Hungary's share and its competitive position, however, decreased on European and world market in the past years. Therefore our research was focused on developing new animal products meeting the changing consumers' demands by their nutritional benefits and by their natural way of production. The study highlights four product s, namely goose - liver produced by considerately fatten up, rabbit meat with low fat and cholesterol levels, beef rich in omega - 3 fatty acids and selenium enriched eggs. The final goal is to form the basis of test - marketing...
Tipo: Conference Paper or Presentation
Palavras-chave: Export; New product; Nutritional benefits; Position; Marketing strategy; Competition; Demand and Price Analysis; Marketing.
Ano: 2006
URL: http://purl.umn.edu/10040

Az élelmiszerlánc szereplői közötti kapcsolatok hazánkban
Provedor de dados: 31
Autores: Popp,   Jozsef; Juhasz,   Aniko.
Hazánkban a válság miatt a keresleti oldalról növekedni képtelen piacon a kiskereskedelmi szereplők a kötelező éves növekedést immár csak a piac újraosztásával érhetik el, ami a kiskereskedők között kíméletlen – horizontális – versenyt eredményez. Ennek eszköze az alapvető termékek esetében a minél alacsonyabban tartott ár. Ezért a kereskedelmi láncok és beszállítóik kapcsolata vegyes képet mutat. A nagy, tőkeerős, elsősorban nemzetközi élelmiszer-feldolgozók és mezőgazdasági beszállítók számára még így is jövedelmező lehet a kereskedelmi láncok által biztosított széles körű piaci jelenlét. Ezzel szemben a hazai szinten nagy, de nem elég tőkeerős hazai beszállítók alkupozíciója rendkívül kényes, számukra még veszteség mellett is létkérdés a kereskedelmi...
Tipo: Article
Palavras-chave: Élelmiszerlánc; Beszállítók; Vevői erő; Koncentráció; Verseny; Food supply chain; Food suppliers; Buyer power; Concentration; Competition; Agribusiness; International Relations/Trade; Marketing.
Ano: 2011
URL: http://purl.umn.edu/119886

Consumer, Manufacturer and Retailer Responses to Health Price Policies: the example of EU Sugar Price Reform on the Soft Drink Market
Provedor de dados: 31
Autores: Bonnet,   Céline; Requillart,   Vincent.
Healthier food diet is likely to prevent numerous non communicable diseases. Then there is a growing interest in evaluating the impact of food price taxation on food consumption. However, strategic reactions of both manufacturers and retailers are missing in empirical analyses. Rather, passive pricing is assumed. Ignoring strategic pricing might lead to under-estimate or over-estimate the impact of food taxation. Based on the example of the soft drink industry, we analyse the bias which is introduced when assuming passive pricing. Using structural econometric model, we first estimate models of vertical relationships between the beverage industry and the retail industry. After selecting the ’best’ model of vertical relationships, we then simulate different...
Tipo: Conference Paper or Presentation
Palavras-chave: Vertical contracts; Two part tariffs; Competition; Manufacturers; Private labels; Retailers; Differentiated products; Soft drinks; Non nested tests; Sugar CMO; Passthrough; Food Consumption/Nutrition/Food Safety; Health Economics and Policy.
Ano: 2011
URL: http://purl.umn.edu/108788

EFECTOS DE LA CERTIFICACIÓN SOBRE LA COMPETITIVIDAD DE LA INDUSTRIA DE LA SÁBILA EN MÉXICO
Provedor de dados: 31
Autores: Alvarez Moreno,   Gumercindo; Rodríguez Garcia,   Roselyn; Flores Montano,   Amelia.
Aloe Vera is the base of a very lucrative business around the world, in which Mexico participates as the main Aloe Vera raw materials producer and exporter country. For the perishable nature of Aloe Vera raw materials, they go under a stabilization process that fulfills the final consumer requirements. Many of the companies certify their raw materials, processes and final products in order to guarantee to the final consumer the origin, purity, and product content, besides the ethical strictness of their promotional and commercial information. The certifying council (International Aloe Science Council) express in their promotion that certified companies are more competitive than those that don't certify their products. However, since the lack of evidences...
Tipo: Article
Palavras-chave: Competition; Aloe Vera processor; Competitive profile; Certification seal; Raw materials.; Agribusiness.
Ano: 2012
URL: http://purl.umn.edu/120500

On Regulation and Competition: Pros and Cons of a Diversified Monopolist
Provedor de dados: 31
Autores: Calzolari,   Giacomo; Scarpa,   Carlo.
We study the regulation of a firm which supplies a regulated service while also operating in a competitive, unregulated sector. If the firm conducts its activities in the two markets jointly, it enjoys economies of scope whose size is the firm’s private information, unknown either to the regulator or to the rival firms. We characterize the unregulated market outcome (with price and quantity competition) and optimal regulation that involves an informational externality to the competitors. Although joint conduct of the activities generates scope economies, it also entails private information, so that regulation is less efficient and the unregulated market too may be adversely affected. Nevertheless, we show that allowing the firm to integrate productions is...
Tipo: Working or Discussion Paper
Palavras-chave: Regulation; Competition; Asymmetric Information; Conglomerate Firms; Multiutility; Scope Economies; Informational Externality; Financial Economics; L51; L43; L52.
Ano: 2009
URL: http://purl.umn.edu/52543

Price transmission along the food supply chain in the European Union
Provedor de dados: 31
Autores: Bukeviciute,   Lina; Dierx,   Adriaan; Ilzkovitz,   Fabienne; Roty,   Guillaume.
Agricultural commodities and consumer food prices have experienced strong variations over the last 2 years, both upwards and downwards. This increased volatility, combined with long-term prospects of rising food prices, highlights the necessity to increase the efficiency of the food supply chain to ensure consumer food prices reflect the evolution of inputs prices. This paper aims at better understanding price transmission  mechanisms along the chain across European Union Member States. Significant differences across Member States in magnitude of pass-through of agricultural commodity prices variations to consumer prices, as well as price transmission asymmetries, suggest potential market fragmentation within the EU. Country-specific regulatory frameworks,...
Tipo: Conference Paper or Presentation
Palavras-chave: Food; Regulation; Market structure; Competition; Pricing.; Financial Economics.
Ano: 2009
URL: http://purl.umn.edu/57987

Healthy Competition in the Animal Health Industry
Provedor de dados: 31
Autores: Buhr,   Brian L.; Holtkamp,   Derald; Sornsen,   Steve.
Tipo: Journal Article
Palavras-chave: Pharmaceutical Industry; Five Forces; Animal Health; Veterinary; Competition; Economics; Agribusiness; Livestock Production/Industries; Q13; Q18; L11; L22; L2; L66.
Ano: 2011
URL: http://purl.umn.edu/104213

Product Market Competition and Human Resource Practices: An Analysis of the Retail Food Sector
Provedor de dados: 31
Autores: Davis,   Elizabeth E.; Freedman,   Matthew; Lane,   Julia; McCall,   Brian P.; Nestoriak,   Nicole; Park,   Timothy A.
The rise of super-centers and the entry of Wal-Mart into food retailing have dramatically altered the competitive environment in the industry. This paper explores the impact of such changes on the labor market practices of traditional food retailers. We use longitudinal data on workers and firms to construct new measures of compensation and employment, and examine how these measures evolve within and across firms in response to changes in product market structure. An additional feature of the analysis is to combine rich case study knowledge about the retail food industry with the new matched employer-employee data from the Census Bureau.
Tipo: Working or Discussion Paper
Palavras-chave: Supermarkets; Human resource practices; Competition; Internal labor market; Wage growth; Labor and Human Capital; Marketing.
Ano: 2005
URL: http://purl.umn.edu/14349

Market Share and Price Setting Behavior For Private Labels and National Brands
Provedor de dados: 31
Autores: Cotterill,   Ronald W.; Putsis,   William P., Jr.; Dhar,   Ravi.
In this paper, we develop a framework for estimating market share and price reaction equations in an attempt to understand the nature of competitive interaction in the market for private label and branded grocery products. Specifically, we employ a Linear Approximate Almost Ideal Demand System (LA/AIDS, Deaton and Muellbauer 1980a), and specify the price reaction equations derived under the LA/AIDS demand specification. This enables us to consistently estimate shareprice relationships, accounting for demand-side and competitive reactions simultaneously. The incorporation of LA/AIDS demands into a structural equation framework represents an important departure from previous demand specifications in competitive analysis. In addition to its rigorous...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Competitive strategy; Private labels; Pricing; Demand and Price Analysis; Industrial Organization.
Ano: 2000
URL: http://purl.umn.edu/25209

Firm-specific information, product differentiation, and industry equilibrium
Provedor de dados: 31
Autores: Perloff,   Jeffrey M.; Salop,   Steven.
Where consumers have imperfect information about specific firms’ prices and lack information about the market, firms have informational market power. In general, improving the consumer’s information about each firm’s price will not necessarily lower average market price. We show, however, that certain types of improvements will lower price. Moreover, a reduction in barriers to entry (e.g., capital costs) will lower price-holding information constant. Where a significant number (but not all) consumers have perfect information, single-price equilibria are impossible.
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Consumers; Consumers' preferences; Consumer education; Mathematical models; Demand elasticity; Economics; Equilibrium; Marketing; Consumer/Household Economics; Demand and Price Analysis.
Ano: 1985
URL: http://purl.umn.edu/47003

Assessing the Competitive Interaction Between Private Labels and National Brands
Provedor de dados: 31
Autores: Cotterill,   Ronald W.; Putsis,   William P., Jr.; Dhar,   Ravi.
In contrast to single-equation cross-sectional studies of private label share, developing a complete understanding of the nature of the competitive interaction between national brands and private labels requires an understanding of the determinants of both demand and strategic pricing decisions by firms. Consequently, we estimate a simultaneous system of share and price for private labels and national brands. From the empirical results, two measures of market response are derived. The unilateral demand elasticity measures the pure “own” demand response, while the residual (or “total”) elasticity also captures the impact of competitive price reaction (Baker and Bresnahan 1985). When taken together, these provide important strategic insights into the pricing...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Competitive strategy; Private labels; Pricing; Demand and Price Analysis.
Ano: 1999
URL: http://purl.umn.edu/25177

Feedlot and Packer Pricing Behavior: Implications for Competition Research
Provedor de dados: 31
Autores: Ward,   Clement E.
Seldom are observed losing bids available in industry data. A special workshop of the Fed Cattle Market Simulator was designed to capture bids for each pen of cattle traded. Data enabled identifying buyer and seller behavior in the price discovery process, both before and after imposed mergers of the two largest and two smallest packer teams. Highest losing bids also were estimated with packer bid functions and compared with observed highest losing bids. An estimated price discovery model indicated market structure as measured by number of buyers was more important than simply the number of bids or size of transactions.
Tipo: Conference Paper or Presentation
Palavras-chave: Buyer behavior; Competition; Fed cattle; Marketing; Pricing; Seller behavior; Livestock Production/Industries.
Ano: 2007
URL: http://purl.umn.edu/7365

Concorrência e estratégias de precificação no sistema agroindustrial do leite
Provedor de dados: 31
Autores: Azevedo,   Paulo Furquim de; Politi,   Ricardo Batista.
This article aims to evaluate the degree of competition in the dairy industry, in the relevant markets of Ultra High Temperature (UHT) milk and pasteurized milk, by means of price transmission and marketing margin behavior. The empirical analysis is based on the model formerly proposed by Houck (1977) and latter detailed by Carman and Sexton (2005).This model analyzes separately the effects of input price increases and reductions on consumer prices, allowing for estimations of price transmission and margin behavior. Cepea-USP and Fipe provide, respectively, weekly input prices and consumer prices, both for the period of December 1999 to December 2005. As a major result, the degree of competition in the UHT relevant market was found to be robustly different...
Tipo: Journal Article
Palavras-chave: Competition; Price transmission; Dairy industry.; Agribusiness; L11; Q13.
Ano: 2008
URL: http://purl.umn.edu/61234

A PRECARIEDADE DO TRANSPORTE RODOVIÁRIO BRASILEIRO PARA O ESCOAMENTO DA PRODUÇÃO DE SOJA DO CENTRO-OESTE: SITUAÇÃO E PERSPECTIVAS
Provedor de dados: 31
Autores: Capacle,   Vivian Helena; Ramos,   Pedro.
A região Centro-Oeste do país se destaca como um pólo produtor de soja e essa produção é escoada, em sua maioria, por meio de rodovias. Pela crise fiscal do Estado, a partir dos anos 80, a malha rodoviária brasileira perde participação nos recursos públicos para investimentos em sua ampliação, conservação e restauração e, essa escassez de investimentos nas rodovias tem reflexos sobre a competitividade internacional da soja dos cerrados, uma vez que o principal modal utilizado para o escoamento dessa produção para os portos das Regiões Sul e Sudeste é o modal rodoviário cujas vias estão em estado precário de conservação, com destaque para trechos das rodovias BR 163 e BR 364 que são vias importantes na região do Centro-Oeste. Por conta disso, 25% da receita...
Tipo: Conference Paper or Presentation
Palavras-chave: Infra-Estrutura de Transportes; Rodovias; Soja; Competitividade; Transportation Infrastructure; Roads; Soy Bean; Competition; Agribusiness.
Ano: 2008
URL: http://purl.umn.edu/109376

The effect of tariffs in markets with vertical restraints
Provedor de dados: 31
Autores: Fargeix,   Andre; Perloff,   Jeffrey M.
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Economics; Equilibrium; Marketing; Mathematical models; Monopolies; Tariff; Welfare economics; Marketing; International Relations/Trade.
Ano: 1987
URL: http://purl.umn.edu/47040

Can health warnings and nutritional information lower welfare?
Provedor de dados: 31
Autores: Perloff,   Jeffrey M.
Tipo: Working or Discussion Paper
Palavras-chave: Benefit-cost analysis; Competition; Health; Monopolies; Nutrition; Welfare economics; Food Security and Poverty; Food Consumption/Nutrition/Food Safety.
Ano: 1981
URL: http://purl.umn.edu/47006

Television Advertising and Soda Demand
Provedor de dados: 31
Autores: Lopez,   Rigoberto A.; Liu,   Yizao; Zhu,   Chen.
This study examines the effects of television advertising on consumer demand for carbonated soft drinks using a random coefficients logit model (BLP) with household and advertising data from seven U.S. cities over a three year period. We find that advertising decreases the price elasticity of demand, indicating that advertising plays predominantly a persuasive, therefore anti-competitive role in this market. Further results show that brand spillover effects are significant and that measuring advertising with gross rating points (GRPs) outperforms measuring it with expenditures, as is conventionally done. Finally, simulation results indicate that eliminating all television advertising would lower market shares of sodas as consumers migrate to other...
Tipo: Presentation
Palavras-chave: Advertising; Demand; Competition; Consumer behavior; Sodas; Carbonated soft drinks; Demand and Price Analysis; Industrial Organization; Marketing; D12; L66; Q18; I18.
Ano: 2012
URL: http://purl.umn.edu/124445

The regional specifity of structural change in agriculture: An assessment of the role of farmers’ strategic behaviour on the land market
Provedor de dados: 31
Autores: Margarian,   Anne.
Among the family-farms in western Germany, significant regional differences are observable. They exist not only with respect to present farm-structure but also with respect to patterns of structural change. In the present paper, the different farm-development-strategies that cause these regional patterns are explained economically. As a central cause for their stability in a competitive environment, the relatedness of agricultural production to the non-renewable factor land is identified. Moreover, the coordination of the different strategies, which results in regional clusters, is shown to evolve endogenously in a model of strategic interaction on the land-market. It is demonstrated that due to the existence of rents of the status quo and resulting...
Tipo: Working or Discussion Paper
Palavras-chave: Market Structure; Firm Behaviour; Equilibria; Rationality; Farming; Complementarity; Competition; Disequilibrium Dynamics; Agriculture; Agribusiness; Agricultural and Food Policy; Farm Management; Institutional and Behavioral Economics.
Ano: 2009
URL: http://purl.umn.edu/59522

Price Transmission and Marketing Margins in the Slovenian Beef and Pork Markets During Transition
Provedor de dados: 31
Autores: Bojnec,   Stefan.
As in many other transition countries processing and marketing margins are also larger in the Slovenian meat market than respective margins in market economies. In addition, margin of the Slovenian pork chain is greater than in the beef chain. Its decline in the pork market indicates an adjustment to more competitive markets. Co-integration models are applied to estimate vertical price transmission and to examine margins and degree of competition in the meat marketing chains. Results indicate the existence of a long run equilibrium regarding vertical price transmission in the beef and pork sectors. Both the farm-gate beef and pork prices are identified as weakly exogenous in the long run. The structural tests imposing a homogeneity restriction suggest a...
Tipo: Conference Paper or Presentation
Palavras-chave: Price transmission; Marketing margin; Co-integration; Competition; Marketing; D4; L1; C3; Q1.
Ano: 2002
URL: http://purl.umn.edu/24789

U.S. Meatpacking: Dynamic Forces of Change in a Mature Industry
Provedor de dados: 31
Autores: Buhr,   Brian L.; Ginn,   Bruce.
Tipo: Journal Article
Palavras-chave: Meatpacking; Five Forces; Competition; Supply Chain; Vertical Coordination; Relevant Markets; Agribusiness; Livestock Production/Industries; Q13; Q18; L11; L22; L2; L66.
Ano: 2011
URL: http://purl.umn.edu/104210

Interconnected firms’ relationships as a source of a competitive advantage
Provedor de dados: 31
Autores: Rudawska,   Iga.
The mainstream economy poses the opinion that a competitive advantage lies in resources, and, consequently - in competences as well - being a share of a single company and remaining under its sole control. Recently, some researchers (e.g. Castaldo, 2007; Lavie, 2006) have revised that approach and tend to emphasise the role of other sources of competitive advantage in business strategy, which embrace new, intangible assets. Such assets are being born and developed only within the inter-firm relationships built in network environment. Thus, the presented paper focuses on relational-based approach towards gaining relational rent. It aims at discussing the sources of an appropriated relational rent and, presenting - after Lavie, a new types of rent extracted...
Tipo: Journal Article
Palavras-chave: Enterprise; Relationship management; Competition; Relational rent; Partnership.; International Development; M10; M31; I11.
Ano: 2010
URL: http://purl.umn.edu/95946

Structure of Dairy Markets: Past, Present, Future
Provedor de dados: 31
Autores: Manchester,   Alden C.; Blayney,   Donald P.
The U.S. dairy industry, many segments of which supported dairy policy changes in the 1996 Federal Agriculture Improvement and Reform Act, is much different than it was 20 or even 10 years ago. This report provides a historical overview of the industry, more detailed examinations of the fluid milk market and selected manufactured dairy product markets, a discussion of future prospects and trends in the industry, and some thoughts on the implications of those prospects and trends for dairy farmers and their organizations, processors, dairy product manufacturers, and retailers.
Tipo: Report
Palavras-chave: Dairy; Butter; Cheese; Nonfat dry milk; Market structure; Pricing; Competition; Livestock Production/Industries; Marketing.
Ano: 1997
URL: http://purl.umn.edu/33929

The dynamic annihilation of a rational competitive fringe by a low-cost dominant firm
Provedor de dados: 31
Autores: Berck,   Peter; Perloff,   Jeffrey M.
A low-cost dominant firm will drive all competitive fringe firms out of the market if all firms have rational expectations; however, the dominant firm will not predate (price below marginal cost). Since a dominant firm will not drive out fringe firms if they have myopic expectations, it may be in the dominant firm’s best interests to inform the fringe. The effects of governmental intervention on the optimal path and welfare are presented.
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Industry; Marketing; Mathematical models.
Ano: 1987
URL: http://purl.umn.edu/43636

Competition, Regulation and Privatisation of Electricity Generation in Developing Countries: Does the Sequencing of the Reforms Matter?
Provedor de dados: 31
Autores: Zhang,   Yingang; Parker,   David; Kirkpatrick,   Colin.
Recent years have seen countries introducing reform of their utility industries with a view to promoting private ownership and competition. This paper studies the effect of the sequencing of privatisation, competition and regulation reforms in electricity generation using data from 25 developing countries for the period 1985 to 2001. A fixed effects panel data model is used. The study finds that establishing an independent regulatory authority and introducing competition before privatisation is correlated with higher electricity generation, higher generation capacity and, in the case of the sequence of competition before privatisation, improved capital utilisation.
Tipo: Working or Discussion Paper
Palavras-chave: Privatisation; Competition; Regulation; Developing economies; Economic performance.; Resource /Energy Economics and Policy; L33; L43; L44; L50; 012; O38; O50.
Ano: 2004
URL: http://purl.umn.edu/30599

Competition and Dynamics in Trade Patterns: Hungarian and Slovenian Agri-Food Trade with the European Unions' Trading Partners
Provedor de dados: 31
Autores: Bojnec,   Stefan; Ferto,   Imre.
Trade balances and unit values in Hungarian and Slovenian bilateral agri-food trade with Austria, Germany and Italy, respectively, to distinguish types of the one-way and the two-way trade flows, categories of price competition and categories of quality competition in the twoway trade flows, their dynamics and stability over time are analyzed. The two-way matched trade flows prevail among trade types. In the matched two-way bilateral agri-food trade there is prevalence of categories of price competition over categories of non-price competition, but varies across trading partners. In Hungarian agri-food trade the first category of successful price competition and the third category of successful non-price or quality competition prevail, suggesting...
Tipo: Conference Paper or Presentation
Palavras-chave: Competition; Trade types; Dynamics; Mobility index; F12; Q17; Q18; International Relations/Trade.
Ano: 2006
URL: http://purl.umn.edu/25760

IS THE EU SUGAR POLICY REFORM LIKELY TO INCREASE OBESITY?
Provedor de dados: 31
Autores: Bonnet,   Céline; Requillart,   Vincent.
National Health authorities recommend a decrease in the consumption of ’added’ sugar. At the same moment, a reform of the Common Organisation of the Sugar Market will lead to a decrease by more than 30% of the sugar price in the EU. Using the example of the soft drink industry, this paper investigates the impact of that reform on the consumption of sugar sweetened beverages. Because the soft drink industry as well as the retail industry are both highly concentrated, using structural econometrics model, we first estimate models of vertical relationships between the beverage industry and the retail industry. After selecting the ’best’ model of vertical relationships, we then simulate the impact of the decrease in sugar price on prices and consumption for...
Tipo: Conference Paper or Presentation
Palavras-chave: Vertical contracts; Two part tariffs; Competition; Manufacturers; Private labels; Retailers; Differentiated products; Soft drinks; Non nested tests; Sugar CMO; Passthrough; Agricultural and Food Policy; Consumer/Household Economics; Demand and Price Analysis; Food Consumption/Nutrition/Food Safety; Food Security and Poverty; Health Economics and Policy.
Ano: 2010
URL: http://purl.umn.edu/116414

Risk, Overconfidence and Production in a Competitive Equilibrium
Provedor de dados: 31
Autores: Just,   David R.; Cao,   Ying; Zilberman,   David.
Previous studies have found underestimation of risk, or overconfidence, to be pervasive. In this paper, we model overconfidence as a reduction in perceived variance. We generalize the analysis of Sandmo and examine the effects of competition on firms displaying overconfidence. Cases for both competitive equilibrium and imperfect competition are investigated. We show that overconfidence may strictly dominate rationality in a competitive market by leading risk averse producers to invest greater amounts and produce more. This leads to a higher average profit, and greater variance of profits, leaving the producer a greater probability of surviving competitive pressures. Despite the greater variance of profits, if enough producers underestimate their risk, they...
Tipo: Conference Paper or Presentation
Palavras-chave: Overconfidence; Misperception; Production; Competition; Production Economics; Risk and Uncertainty.
Ano: 2009
URL: http://purl.umn.edu/49161

Market Competition, Institutions, and Contracting Outcomes: Preliminary Model and Experimental Results
Provedor de dados: 31
Autores: MacDonald,   James M.; Wu,   Steven Y.
Tipo: Working or Discussion Paper
Palavras-chave: Contracts; Competition; Market Power; Enforcement; Institutions; Agribusiness; Industrial Organization; Institutional and Behavioral Economics; Production Economics; C91; D02; D43; D86.
Ano: 2009
URL: http://purl.umn.edu/50625

The changing federated relationship between local and regional cooperatives
Provedor de dados: 31
Autores: Hogeland,   Julie A.
The evolution of the federated relationship between local and regional cooperatives is examined from the perspective of local cooperatives’ need for commodity-based farm supplies and regional cooperatives’ identity as food companies. Because locals want many competing bids for the supplies they purchase, they resist a strong and close affiliation with regional cooperatives, which then find themselves with excess capacity. Regionals have responded by instituting tighter bonds with selected local cooperatives operating as "internal supply networks," in exchange for certain benefits. This adaptation reduces the impact of divergent goals among regionals and locals within the federated system.
Tipo: Report
Palavras-chave: Cooperatives; Federation; Networks; Competition; Regionalization.; Agribusiness.
Ano: 2002
URL: http://purl.umn.edu/44645

Competitiveness of the Polish Food Sector after the accession to the European Union
Provedor de dados: 31
Autores: Szczepaniak,   Iwona; Szczegolska,   Monika.
The paper focuses on the competitiveness as a driving force of market economy. The analyses of the results of foreign trade in agricultural and food products confirm that Polish agro-food sector is well prepared for operation on the Common European Market. Food producers have taken advantage of their competitive edge, mainly in terms of pricing. Nevertheless, consumers form other EU countries also accept quality features of Polish food. However, in order to maintain their position on the Common European Market, Polish producers should attach even greater attention to the promotion of their products.
Tipo: Conference Paper or Presentation
Palavras-chave: Competition; Competitive edge; Agricultural and food products; Foreign trade; Prices.; Agribusiness.
Ano: 2007
URL: http://purl.umn.edu/7802

The Effects of Different Political Schemes on the Willingness to Invest, Firm Profitability and Economic Efficiency in the Dairy Sector - An Agent-Based Real Options Approach-
Provedor de dados: 31
Autores: Feil,   Jan-Henning; Musshoff,   Oliver; Balmann,   Alfons.
In recent years, the dairy sector has been exposed to strong changes in general conditions and extreme fluctuations in milk prices. Farmers and lobbyists have therefore asked politicians for additional market regulation. In this paper an agent-based real options market model is developed, which allows the analysis of the effects of different political schemes on the willingness to invest, firm profitability and economic efficiency in the dairy sector. The model results show that political schemes generally increase the willingness to invest in competitive markets under consideration of real options effects. However, they do not offer any substantial financial benefits to the producers and can cause a significant reduction in welfare. Furthermore, the...
Tipo: Conference Paper or Presentation
Palavras-chave: Real Options; Competition; Policy Impact Analysis; Dairy Sector; Agricultural and Food Policy; D81; Q12; Q18.
Ano: 2011
URL: http://purl.umn.edu/100039

Two-Part Tariffs versus Linear Pricing Between Manufacturers and Retailers: Empirical Tests on Differentiated Products Markets
Provedor de dados: 31
Autores: Bonnet,   Céline; Dubois,   Pierre; Simioni,   Michel.
We present a methodology allowing to introduce manufacturers and retailers vertical contracting in their pricing strategies on a differentiated product market. We consider in particular two types of non linear pricing relationships, one where resale price maintenance is used with two part tariffs contracts and one where no resale price maintenance is allowed in two part tariffs contracts. Our contribution allows to recover price-cost margins from estimates of demand parameters both under linear pricing models and two part tariffs. The methodology allows then to test between different hypothesis on the contracting and pricing relationships between manufacturers and retailers in the supermarket industry using exogenous variables supposed to shift the...
Tipo: Conference Paper or Presentation
Palavras-chave: Vertical contracts; Two part tariffs; Double marginalization; Collusion; Competition; Manufacturers; Retailers; Differentiated products; Water; Non nested tests; Industrial Organization; L13; L81; C12; C33.
Ano: 2006
URL: http://purl.umn.edu/25685

Equilibrium with product differentiation
Provedor de dados: 31
Autores: Perloff,   Jeffrey M.; Salop,   Steven.
Tipo: Working or Discussion Paper
Palavras-chave: Brands; Competition; Consumers' preferences; Monopolies; Consumer/Household Economics.
Ano: 1984
URL: http://purl.umn.edu/47004

Dynamic Changes in Market Structure and Competition in the Corn and Soybean Seed Sector
Provedor de dados: 31
Autores: Wilson,   William W.; Dahl,   Bruce L.
The purpose of this paper is to analyze the dynamics of R&amp;D investments, and the structure of the seed distribution sector using novel data sets that have not been used before to describe competition in these industries. The results describe four sets of issues of particular importance. One is that while all agbiotechology firms have increased their R&amp;D expenditures, there have been sharp differences in the scope of this spending. Most important is that this has spawned the growth in what is now referred as “seeds and traits.” Second, a large number of future traits will be commercialized in the coming years. A third set of results indicates that one firm grew its market share by 14% and a portion of this growth has been through acquisition. The...
Tipo: Report
Palavras-chave: Agbiotechnology; Grain seeds; Competition; Agribusiness; Crop Production/Industries; Demand and Price Analysis.
Ano: 2010
URL: http://purl.umn.edu/58487

Do prices fall faster when Wal-Mart is around? The effect of competition and reputation on cost pass-through and price adjustment
Provedor de dados: 31
Autores: Martens,   M. Andrea.
This study analyzes Wal-Mart’s pricing practices and its inﬂuence on competitors’ input cost transmission. Previous attempts to analyze Wal-Mart’s pricing strategy in the United States have been limited by the company’s refusal to provide scanner data to third party research  ﬁrms such as AC Nielsen. This is the ﬁrst study to observe Wal-Mart’s prices over an extended period of time. Using weekly-store level price data between 2001 and 2006 that government oﬃcials collected in 12 Mexican cities, I ﬁnd that Wal-Mart adjusts its prices 1/3-3 times slower to wholesale price increases than other retailers and responds 5-7 times faster to wholesale price decreases than its competitors. This evidence is robust to the comparison of Wal-Mart to other hypermarkets...
Tipo: Conference Paper or Presentation
Palavras-chave: Wal-Mart; Cost pass-through; Competition; Agribusiness; Industrial Organization.
Ano: 2009
URL: http://purl.umn.edu/49459

Grower representation and its impact on the governance structure of the Australian Grains Industry
Provedor de dados: 31
Autores: Farrell,   Terence C.
The Australian wheat industry has changed considerably in structure and governance during the past 15 years. The most important changes have been the deregulation of the domestic market and privitisation of the former Australian Wheat Board into AWB Limited. Through these changes growers have become shareholders in the various companies. Governance of the monopolistic relationship between AWB Limited and AWB International by the Federal Minister of Agriculture and the Grains Council of Australia through the Wheat Export Authority has proved ineffective. Hence a national organisation that represents shareholders is recommended to increase grower governance of the supply chain and marketing of wheat.
Tipo: Conference Paper or Presentation
Palavras-chave: Grain; Marketing; Infrastructure; Competition; Governance; Agricultural and Food Policy; Crop Production/Industries; Marketing.
Ano: 2004
URL: http://purl.umn.edu/58447

Competition, Evolution and Optimisation: Comparisons of Models in Economics and Ecology
Provedor de dados: 31
Autores: Tisdell,   Clement A.
Discusses concepts of competition in economics and ecology and the relevance of evolution to both subjects. It is suggested that although speciation or increasing biodiversity tends to occur in undisturbed ecological systems, the opposite trend may occur in economic systems. Competition based on optimisation plays a significant role in theories of the evolution of species and some theories of the evolution of business or industrial structures. But evolution does not result in optimal selection of species or businesses for the future, and there is scope for doubt about what is being optimised by survivors in the evolutionary process. Ecological or biological theories of intra-specific competition involving scramble and contest competition are outlined and...
Tipo: Working or Discussion Paper
Palavras-chave: Biology; Competition; Evolution; Market development; Optimisation; Environmental Economics and Policy.
Ano: 2001
URL: http://purl.umn.edu/48384

Share, Price and Category Expenditure -- Geographic Market Effects and Private Labels
Provedor de dados: 31
Autores: Putsis,   William P., Jr.; Cotterill,   Ronald W.
Focusing on the interaction between national brands and private labels, this paper has two main empirical contributions: i) a simultaneous system of demand (share), price and expenditure equations is estimated, and ii) differences in the structure of the local geographic market are incorporated into the analysis. The former represents an important step in understanding the complete nature of private label and national brand interaction, while the latter is important for understanding the impact of the local retail environment on market behavior. IRI scanner data from 1991 and 1992 are used to estimate the three-equation system across 135 food product categories and 59 geographic markets. The results suggest that concentration at both the manufacturer and...
Tipo: Working or Discussion Paper
Palavras-chave: Competition; Private labels; Industrial organization; Demand and Price Analysis; Industrial Organization; Marketing.
Ano: 2000
URL: http://purl.umn.edu/25166

Article 82 EC – The Problems and The Solution
Provedor de dados: 31
Autores: Lang,   John T.
The Commission's Guidance paper on exclusionary abuse under Article 82 EC is open to three fundamental criticisms.  First, it leads to less legal certainty, because the rules suggested are vague and imprecise, because dominant companies will not have the information needed to apply them, and because the Commission is trying to change the law, which it has no power to do. Second, it would lead to some anticompetitive effects, because in practice it discourages price competition, by discouraging individualised price negotiations and retroactive rebates, and by suggesting that the Commission will protect not-yet-as-efficient competitors from price competition. Third, it leads to too many "false positives", i.e., findings of exclusionary abuse that are not...
Tipo: Working or Discussion Paper
Palavras-chave: Article 82EC; Competition; Abuse; Institutional and Behavioral Economics; K21.
Ano: 2009
URL: http://purl.umn.edu/54282

Policy Impact Analysis on Investments and Disinvestments under Competition: A Real Options Approach
Provedor de dados: 31
Autores: Feil,   Jan-Henning; Musshoff,   Oliver.
In consequence of changes in general conditions, a higher level of investments and disinvestments in agriculture can be expected. To date, however, there are no policy impact analyses on both investments and disinvestments in competitive agricultural markets in a dynamic-stochastic context. This paper aims to develop a conceptual real options market model, which allows the impact assessment of different political schemes on investment and disinvestment thresholds and the sectoral welfare. Exemplarily, the effects of price floors, investment subsidies and production ceilings are analysed. The results show that the consideration of limited reversibility, that is disinvestments, is of relevance as it can impact the assessment of specific policies.
Tipo: Presentation
Palavras-chave: Real options; Competition; Policy impact analysis; Genetic algoritms; Marketing; Political Economy.
Ano: 2012
URL: http://purl.umn.edu/124294

Assessing Oligopoly and Oligopsony Power in the U.S. Catfish Industry
Provedor de dados: 31
Autores: Bouras,   David; Engle,   Carole R.
This paper addresses the issue of competition in the U.S. catfish industry. To this end, a conjectural variation oligopolistic model was developed. The model was estimated econometrically using the Generalized Method of Moments (GMM) procedure. Chi-square analysis implied that catfish processors do not exert market power over farmers or over consumers. The conjectural elasticity was estimated to be 0.073, the oligopoly power index 0.28, and the oligopsony power index 0.68, and none of these values were statistically significant. The results support competitive behavior of the catfish processing sector.
Tipo: Journal Article
Palavras-chave: Competition; Conjectural variation model; U.S. catfish industry; Agribusiness; Livestock Production/Industries.
Ano: 2007
URL: http://purl.umn.edu/62284

Nutritional ecology of blowflies (Diptera, Calliphoridae): estimates of critical larval weight for pupation on two different
Provedor de dados: 92
Autores: Ribeiro,Cássio da Silva; Von Zuben,Cláudio José.
Under natural environmental conditions, blowflies utilize discrete and ephemeral feeding resources such as decaying carcasses. Competition for food on such feeding substrates is usually very severe, and only the individuals that are capable of attaining the critical larval weight for pupation will be able to survive. This critical weight is hitherto unknown for several blowfly species; therefore, the current work is aimed at obtaining such a critical value for four blowfly species of the genera Chrysomya and Lucilia, deploying two types of feeding substrate, namely, artificial diet and macerated bovine meat. On the whole, the critical weights ranged from 30 to 35 mg. The lowest larval weight which permitted pupation was 30.0 mg for Chrysomya megacephala...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Calliphorids; Competition; Food; Larvae; Minimum weight.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0085-56262010000400019

First report of interspecific facultative social parasitism in the paper wasp genus Mischocyttarus Saussure (Hymenoptera, Vespidae)
Provedor de dados: 92
Autores: Montagna,Thiago S.; Neves,Érika F.; Antonialli-Junior,William F.
First report of interspecific facultative social parasitism in the paper wasp genus Mischocyttarus Saussure (Hymenoptera, Vespidae). Parasitism of colonies of the social wasp Mischocyttarus cerberus Ducke, 1918 by females of Mischocyttarus consimilis Zikán, 1949 was observed in a rural area of Dourados, state of Mato Grosso do Sul, Brazil. In all monitored cases, the invasion occurred in the pre-emergence colony stage, generally by a single female of M. consimilis. The period of establishment of the foreign female in the host colony was marked by antagonistic behaviors between the host female and the invasive. In general, the architecture of the parasitized nest was modified from the typical architecture of the host species nest.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Interaction; Independent foundation; Neotropical wasp.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0085-56262012000200016

Seasonality and temporal structuration of Alticini community (Coleoptera, Chrysomelidae, Galerucinae) in the Araucaria Forest of Parana, Brazil
Provedor de dados: 92
Autores: Linzmeier,Adelita Maria; Ribeiro-Costa,Cibele Stramare.
Seasonality was studied for Alticini trapped with malaise over a period of two years in the Vila Velha State Park, Parana, Brazil. Coleoptera, Chrysomelidae and Alticini showed seasonal distribution, with the highest abundance during spring and summer months. The abundance peaks of these groups were not synchronized. Of all environmental variables tested, photoperiod had the larger effect on the distributional patterns of Coleoptera, Chrysomelidae and Alticini. Also, Chrysomelidae and Alticini probably are related to the quality and availability of host-plants. When richness was high there was a greater similarity among seasons of different years. However, when richness was not pronounced, seasons showed more similarity within the same year than between...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Abundance; Community structure; Competition; Herbivorous; Seasonality.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0085-56262008000200009

Heterospecific sociality of birds on beaches from southeastern Brazil
Provedor de dados: 103
Autores: Cestari,César.
Studies on the sociality of heterospecific assemblages of birds have promoted a greater understanding of the types of interactions and survivorship between coexisting species. This study verified the group compositions in bird assemblages and analyzed the sociality of migratory and resident species on sandy beaches of southeastern Brazil. A transect was established on the median portion of beaches and all the groups of bird species (monospecific, heterospecific) and solitary individuals were registered four days per month from November 2006 to April 2007. The sociality of each species was calculated by its frequency in heterospecific groups, its proportional number of contacts with other species in heterospecific groups, and the number of species that it...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Association; Competition; Heterospecific groups; Nearctic migrants; Shorebirds.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702009000400002

Advertisement call of Dendropsophus microps (Anura: Hylidae) from two populations from southeastern Brazil
Provedor de dados: 103
Autores: Forti,Lucas Rodriguez; Márquez,Rafael; Bertoluci,Jaime.
In anurans, acoustic communication is a major mechanism of pre-zygotic isolation, since it carries information about species recognition. Detailed descriptions of the acoustic properties of anuran advertisement calls provide important data to taxonomist and to the understanding of the evolution of the group. Herein we re-describe the advertisement call of the hylid frog Dendropsophus microps (Peters, 1872) after analyzing a larger sample than that of previous descriptions. We also compare the acoustic properties of the call in two populations and discuss the effect of the presence of the sister species, Dendropsophus giesleri (Mertens, 1950), a potential competitor, in one of the populations. Additionally, we provide information on calling sites and size...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Acoustic traits; Amphibia; Bioacoustics; Call evolution; Competition.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702015000300187

Temporal differences in breeding site use between tits and mice
Provedor de dados: 103
Autores: Suzuki,Kei K.; Yoshida,Tomoya; Yamane,Yutaka; Shimamoto,Tatsuki; Furukawa,Ryuji G.; Yanagawa,Hisashi.
ABSTRACT Describing the interactions among cavity breeders is key to understanding their breeding ecology. In this study the temporal difference in cavity use between the great tit, Parus major (Linnaeus, 1758) and the small Japanese field mice, Apodemus argenteus (Temminck, 1845) is investigated, as a first step for clarifying the interaction between bird and mammal cavity breeders. Forty-seven nest boxes were installed on tree trunks in two urban forests of Hokkaido Island, Japan, and the breeding nests of tits and mice were found in 34 and 11 boxes, respectively. The tits used the nest boxes throughout the breeding season, from May to July. In contrast, mice breeding nests were found in the last half of the breeding season, from July to October. Our...
Tipo: Info:eu-repo/semantics/other
Palavras-chave: Bird-mammal interaction; Breeding ecology; Competition; Reproduction strategy; Tree cavities.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702017000100500

Biology, distribution and geographic variation of loliginid squids (Mollusca: Cephalopoda) off southwestern Atlantic
Provedor de dados: 103
Autores: Martins,Rodrigo Silvestre; Juanicó,Marcelo.
ABSTRACT The biology and ecology of southwestern Atlantic loliginid squids have been intensively researched in the last few decades, mostly off the Brazilian southern coast. However, information gathered by scientific research cruisers, either past or recent, is limited. Three species of loliginid squids - the warm-tempered Doryteuthis sanpaulensis (Brakoniecki, 1984), plus the tropical D. pleii (Blainville, 1823) and Lolliguncula brevis (Blainville, 1823) - were sampled along 16 degrees of latitude on the southwestern Atlantic (22-38°S). The samples were obtained mostly from oceanographic surveys, but also included squids caught by commercial fisheries, and a few specimens from museum collections. Squid response to abiotic variables, morphological...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Morphology; Myopsida; Population biology; Reproduction.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702018000100337

Grazing management strategies for massaigrass-forage peanut pastures: 1. dynamics of sward condition and botanical composition
Provedor de dados: 96
Autores: Andrade,Carlos Mauricio Soares de; Garcia,Rasmo; Valentim,Judson Ferreira; Pereira,Odilon Gomes.
This study was carried out from October 2002 to December 2003 to evaluate the dynamics of sward condition and botanical composition of a mixed massaigrass (Panicum maximum x P. infestum, cv. Massai) and forage peanut (Arachis pintoi Ac 01) pasture, intermittently stocked at three daily herbage allowance levels (9.0, 14.5 and 18.4% live weight). Sward condition was characterized in each grazing cycle in terms of the pre and post-grazing sward height, forage mass and percentage of bare ground. Botanical composition (grass, legume and weeds) was evaluated before each grazing period. Sward height and forage mass increased linearly with increasing herbage allowance (HA) levels, and higher values were observed during the rainy season. Percentage of bare ground...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Arachis pintoi; Competition; Legume; Panicum maximum; Persistence; Western Amazon.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982006000200002

The coexistence of species La coexistencia de especies
Provedor de dados: 97
Autores: GORDON,CALEB E.
This paper is a critical literature review on the topic of the coexistence of similar species within ecological communities. A conceptual framework is provided for dividing coexistence studies and concepts into three distinct time scales. The first six sections deal primarily with ecological-scale, or mesoscale coexistence, defined as coexistence in the classic sense of the competitive exclusion principle and Lotka-Volterra models, wherein interacting populations have had enough time to reach equilibrium. The first four sections briefly review resource partitioning studies and competitive coexistence models, and discuss the relative contributions of, and interaction between empirical and theoretical approaches to the problem of ecological-scale...
Tipo: Journal article
Palavras-chave: Coexistence; Competition; Community structure; Resource partitioning; Niche.
Ano: 2000
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000100016

Floristic and phytosociology of weeds in pastures in Maranhão State, Northeast Brazil
Provedor de dados: 124
Autores: Costa,Jaílson Penha; Mesquita,Mário Luiz Ribeiro.
ABSTRACT Knowledge of weed floristic composition and phytosociology are key factors for improving weed management in pastures. Information on weed species that occur in pastures in Northeast Brazil, particularly in Maranhão State is very limited. It is, therefore, important, to search for information to help farmers to control weeds in livestock farming. This paper describes the weed flora diversity and community structure parameters, including density, frequency, abundance and importance value for each weed species found in five pastures of same age and management in Maranhão State, Northeast Brazil. The weed survey was carried out using a wooden frame (80 cm x 30 cm) placed randomly on the soil surface 30 times in each pasture (n = 150). Weeds were...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Eragrostis ciliaris; Competition; Biological invasion; Allelopathy; Cyperus rotundus.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902016000200414

Production and nutritive value of pastures in integrated livestock production systems: shading and management effects
Provedor de dados: 63
Autores: Pezzopane,José Ricardo Macedo; Bernardi,Alberto Carlos de Campos; Azenha,Mariana Vieira; Oliveira,Patricia Perondi Anchão; Bosi,Cristiam; Pedroso,André de Faria; Esteves,Sérgio Novita.
ABSTRACT This study aimed to evaluate the production characteristics of pastures in integrated livestock production systems. For that, an experiment was carried out in São Carlos, SP, Brazil, from 2013 to 2015. Forage development, production and nutritive value were evaluated in five beef cattle production systems: extensive continuous stocking (Urochloa decumbens) = EXT; intensive = INT; crop-livestock = iCL; livestock-forest = iLF and crop-livestock-forest = iCLF. Rotational stocking pastures in INT, iCL, iLF and iCLF systems were established with Urochloa brizantha cv. BRS Piatã. In iCL and iCLF, pastures were renovated by resowing the grass simultaneously with corn. In iLF and iCLF, eucalyptus (Eucalyptus urograndis clone GG100) was planted in Apr 2011...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Urochloa brizantha; Eucalyptus urograndis; Solar radiation; Competition; Sustainability.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000200402

Brachiaria decumbens supresses the initial growth of Coffea arabica
Provedor de dados: 63
Autores: Dias,Guilherme Faus da Silva; Alves,Pedro Luís da Costa Aguiar; Dias,Tomás Carneiro de Souza.
Brachiaria decumbens is becoming one the most common weeds growing in young coffee orchards because, besides its fast growth and difficulty of control, new coffee orchards are usually established in pasture areas. In order to verify the effect of B. decumbens plant density on the early growth of coffee (Coffea arabica L. cv. Catuaí Amarelo), a competition experiment was conducted under semi-controlled humidity conditions. Soil collected in a Typic Haplustox was placed in 70 L asbestos cement boxes and one coffee seedling was planted in each box. The B. decumbens seedlings were transplanted to the boxes at the 2-4 leaf stage. Treatments consisted of 0, 4, 8, 12, 16, 20, 24, 36, 48, and 60 weeds m-2. The experimental period started 120 days after...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Weed; Coffee; Competition; Growth suppression.
Ano: 2004
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162004000600003

Adsorption of Cd, Cu, Ni and Zn in tropical soils under competitive and non-competitive systems
Provedor de dados: 63
Autores: Moreira,Cindy Silva; Alleoni,Luís Reynaldo Ferracciú.
The adsorption of heavy metals in soils affects their behavior in the environment and their bioavailability to plants. The knowledge of the adsorption mechanisms in competitive systems allows a more realistic evaluation of the metals' behavior in the soil than the single metal adsorption. The objectives of this study were (i) to evaluate Cd, Cu, Ni, and Zn adsorption in 14 surface samples (0-0.2 m) of representative soils of the Brazilian humid-tropical region, in competitive and non-competitive systems, and (ii) to establish metal affinity sequences for each soil, based in the maximum adsorption capacity (MAC) estimated by the Langmuir model. The Rhodic Eutrudox, the Kandiudalf Eutrudox, the Arenic Hapludalf, the Arenic Hapludult and the Typic Argiudoll...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Heavy metals; Competition; Tropical soil.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000300008

ศึกษาการแข่งขันของวัชพืชและการใช้สารเคมีควบคุมและกำจัดวัชพืชในลินิน
Provedor de dados: 106
Autores: Somchai Lakmuang.
Thesis (M.Sc. in Agriculture)
Tipo: PhysicalObject
Palavras-chave: Linseed; Competition; Chemical weed controls; ลินิน; สารเคมีกำจัดวัชพืช; การแข่งขันของวัชพืช; ผลผลิต.
Ano: 1990
URL: http://anchan.lib.ku.ac.th/agnet/handle/001/5460

Territorial-like defensive behavior of floral resources by Heliconius ethilla narcaea Godart over H. sara apseudes (Hübner) (Lepidoptera, Nymphalidae, Heliconiinae)
Provedor de dados: 104
Autores: Rocha,Carlos Frederico Duarte da; Duarte,Marcelo.
The use of nectar and pollen of a bromeliad by two heliconiine butterflies, Heliconius ethilla narcaea Godart, 1819 and H. sara apseudes (Hübner, [1813]) (Lepidoptera, Nymphalidae, Heliconiinae), is herein reported. Observations were made during a pollination study of Aechmea gracilis Lindman (Bromeliaceae, Bromelioidea) in a second-growth forest of the village Vila Dois Rios, Ilha Grande, Rio de Janeiro State, southeastern Brazil. Field observations showed that H. ethilla can be more aggressive than H. sara in exploiting A. gracilis floral resources. Temporal differences in the use of these resources were also observed: H. sara remained comparatively less time on flowers than H. ethilla.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Lepidoptera; Heliconius; Pollination; Aechmea gracilis; Competition; Home range.
Ano: 2001
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-81752001000500027

Do polyembryonic seeds of Carapa surinamensis (Meliaceae) have advantages for seedling development?
Provedor de dados: 36
Autores: FERREIRA,Débora Najara de SOUZA; CAMARGO,José Luís Campana; FERRAZ,Isolde Dorothea Kossmann.
ABSTRACT Polyembryony is the differentiation and development of multiple embryos in a single seed. This characteristic can provide advantages, as more than one embryo is produced with the same amount of resources, and the probability of establishment of at least one seedling increases. However, sibling seedlings may also increase competition, affecting development and survival. In the present study, the possible advantages and disadvantages of polyembryony were analyzed in the initial establishment of seedlings of Carapa surinamensis (Meliaceae), a tree species that produces monoembryonic or polyembryonic seeds. In this regard, the development of single seedlings was compared with a pair of seedlings emerging from polyembryonic seeds. We compared the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Polyembryony; Andiroba; Crabwood; Seedling production; Competition.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672019000200097

DISTRIBUTION AND FEEDING ECOLOGY OF THE AFRICAN TILAPIA Oreochromis mossambicus (TELEOSTEI, PERCIFORMES, CICHLIDAE) IN SURINAME (SOUTH AMERICA) WITH COMMENTS ON THE TILAPIA-KWIKWI (Hoplosternum littorale) (TELEOSTEI, SILURIFORMEs, CALLICHTHYIDAE) INTERACTION
Provedor de dados: 36
Autores: Η. ΜΟL,Jan; VAN DER LUGT,Frank L.
The geographical distribution of the African Tilapia Oreochromis mossambicusin Suriname is restricted to a narrow strip of land along the Atlantic coast. Within the coastal plain, O. mossambicusoccurs in brackish lagoons, oligohaline canals, and shell-sand pit lakes. Physico-chemical characteristics and phytoplankton composition of representative Tilapia water bodies are described. Blue-green algae and fine flocculent detritus are dominant food items in the diet of the Tilapia, while Rotifera and microcrustacea are also important in the diet of larvae and juveniles. Intraspecific diet overlap among ontogenetic stages of the Tilapia did not differ significantly from 1, which means that these diets showed complete overlap. Interspecific diet overlap between...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Oreochromis mossambicus; Hoplosternum littorale; Distribution; Diet overlap; Competition; Suriname.
Ano: 1995
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59671995000200101

THE IMPORTANCE OF ANTIMICROBIAL COMPOUNDS PRODUCED BY BENEFICIAL BACTERIA ON THE BIOCONTROL OF PHYTOPATHOGENS
Provedor de dados: 37
Autores: CESA-LUNA,Catherine; BAEZ,Antonino; QUINTERO-HERNÁNDEZ,Verónica; CRUZ-ENRÍQUEZ,Joel DE LA; CASTAÑEDA-ANTONIO,Ma Dolores; MUÑOZ-ROJAS,Jesús.
ABSTRACT Bacteria produce antimicrobial compounds to compete for nutrients and space in a particular habitat. Antagonistic interactions can be evaluated by several methodologies including the double-layer agar and simultaneous inhibition assays. Among the well-known inhibitory substances produced by bacteria are the broad-spectrum antibiotics, organic acids, siderophores, antifungal, and bacteriocins. The most studied bacterial genera able to produce these inhibitory substances are Enterococcus, Lactococcus, Streptomyces, Bacillus, Pseudomonas, Klebsiella, Escherichia, and Burkholderia. Some beneficial bacteria can promote plant growth and degrade toxic compounds in the environment representing an attractive solution to diverse issues in agriculture and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Antagonism; Antibiotic; Competition; Inhibition; PGPR.
Ano: 2020
URL: http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0120-548X2020000100140

Floristic diversity of the soil weed seed bank in a rice-growing area of Brazil: in situ and ex situ evaluation
Provedor de dados: 39
Autores: Mesquita,Mário Luiz Ribeiro; Andrade,Leonaldo Alves de; Pereira,Walter Esfrain.
The objective of this study was to compare the ex situ and in situ floristic diversity of the soil weed seed bank of a rice field in northeastern Brazil. In a rice field in the county of Bacabal, located in the state of Maranhão, thirty 25-m² plots were laid out. From 15 plots, soil samples (6/plot; n = 90) were taken with a soil probe (25 × 16 × 3 cm) and placed in aluminum trays in the greenhouse. From the remaining 15 plots, weed samples (6/plot; n = 90) were taken with the same soil probe. The number of seeds was estimated by germination. We evaluated the numbers of species and individuals, as well as the density, frequency, abundance and importance value (IV) for each species. Diversity was computed by the Shannon index (H'). We recorded 13,892...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Cyperaceae; Competition; Biological invasion; Phytosociology; Smallholder farmers.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062013000300001

Phylogenetic community structure reveals differences in plant community assembly of an oligotrophic white-sand ecosystem from the Brazilian Atlantic Forest
Provedor de dados: 39
Autores: Gastauer,Markus; Saporetti-Junior,Amílcar W.; Valladares,Fernando; Meira-Neto,João A. A.
ABSTRACT Mussununga, an oligotrophic sandy savanna ecosystem, comprises distinct physiognomies along fire, water and nutrient availability gradients. Grasslands and woodlands are constrained at the opposite poles of these gradients, with grasslands occurring in areas with poorer soils and higher levels of both water-stress and fire intensity. According to the stress-dominance hypothesis, one might expect the importance of competition for community assembly to increase from grasslands to woodlands. Assuming conservation of ecological niches within evolutionary lineages, this should increase phylogenetic overdispersion from grasslands towards woodlands. To test this, we calculated phylogenetic diversity and community structure using different null models as...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Environmental filters; Mussunungas; Savanna woodlands; Stress-dominance hypothesis.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062017000400531

Allelopathic research in Brazil
Provedor de dados: 39
Autores: Reigosa,Manuel; Gomes,Anabele Stefânia; Ferreira,Alfredo Gui; Borghetti,Fabian.
In this article, we review allelopathy studies conducted in Brazil or involving plant species that occur in the country. Conceptions and misconceptions associated with allelopathy, as well as some international criteria to be applied in allelopathic research, are presented and discussed. We observed a sharp increase in the number of papers on this subject conducted in Brazil between 1991 and 2010. However, most studies are conducted under laboratory conditions, lack a clear hypothesis or a solid justification, and typically make use of target species that do not co-exist with the donor species under natural conditions. We also found that most studies do not take the additional steps in order to purify and identify the bioactive molecules. We recommend that...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Allelopathy; Allelochemicals; Competition; Interference; Phytotoxicity; Weed control.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062013000400001

Implications of global climate change for the development and ecological interactions between two key Amazonian aquatic macrophytes
Provedor de dados: 39
Autores: Souza,Sthefanie do Nascimento Gomes de; Piedade,Maria Teresa Fernandez; Demarchi,Layon Oreste; Lopes,Aline.
ABSTRACT Amazon wetlands are among the most vulnerable ecosystem to be impacted by climate change, which may increase the frequency of extreme droughts and floods. We used Eichhornia crassipes and Pistia stratiotes, two abundant aquatic plants in the Amazon floodplains, to evaluate the effects of combined temperature and [CO2] increase on growth, physiology and ecological interactions. Individual and paired plants were deposited for three weeks in a microcosm under four IPCC scenarios: control (current temperature/CO2), mild (control + 1.5 ºC, 200 ppm CO2), intermediate (control + 2.5 ºC, 450 ppm CO2) and extreme (control + 3.5 ºC, 850 ppm CO2). P. stratiotes died after three weeks in the intermediate and extreme treatments; E. crassipes experienced no...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Biomass; Competition; Eichhornia crassipes; Pistia stratiotes; Wetlands.
Ano: 2021
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062021005002204

Spatial patterns of two co-occurring savanna and forest tree species in a dense fire-protected savanna fragment
Provedor de dados: 39
Autores: Costa,Rafael Carvalho da; Santos,Flavio Antonio Maës dos.
ABSTRACT Savanna-forest transition under fire-exclusion could be explained by differential competitive performance of savanna and forest species under shading/fire-exclusion. Aiming to understand strategies related to either habitat affinity, we investigated spatial patterns of a savanna and a forest species in a fire-protected savanna. We predicted that: savanna species would have lower abundance than the forest species due to a restriction in the number of open microsites; segregation of size classes and a trend from clumping to regularity with size for forest species due to absence of microsite limitation and intra-specifc competition; and spatial association and increasing clustering with size for savanna species due to microsite limitation. To test...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Cerrado; Competition; Fire; Microsite limitation; Recruitment; SADIE; Savanna; Spatial patterns.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062016000400577

Soil weed seed bank in situ and ex situ at a smallholder field in Maranhão State, northeastern Brazil
Provedor de dados: 1
Autores: Mesquita, Mário Luiz Ribeiro; Andrade, Leonaldo Alves; Pereira, Walter Esfrain.
The objective of this research was to assess the density, floristic composition,  phytosociology and diversity of a soil weed seed bank ex situ by germination in a greenhouse and in situ by weed sampling on a smallholder corn field located in Lago Verde County, Maranhão State. Fifteen pairs of 25 m2 plots were designated. In half of these plots, 90 soil samples were collected with an open metal template measuring 25 x 16 x 3 cm and placed in a greenhouse to germinate. In the other half, 90 weed samples were collected using the same metal template. We recorded a total of 1,998 individuals from 40 species, 31 genera and 16 families, from which 659 individuals germinated in situ and 1,339 exsitu. Density was higher ex situ, with 372 plants m-2. The Cyperaceae...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Ciências Agrárias  Fitotecnia cyperaceae; Competition; Biological invasion; Phytosociology; Smallholder farmers Botânica Sistemática  Plantas Invasoras.
Ano: 2014
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/19360

Período anterior à interferência das plantas daninhas para a cultivar de feijoeiro ‘Rubi’ em função do espaçamento e da densidade de semeadura - doi: 10.4025/actasciagron.v33i2.5646
Provedor de dados: 1
Autores: Scholten, Roger; Unesp-Jaboticabal; Parreira, Mariana Casari; Unesp-Jaboticabal; Alves, Pedro Luis da Costa Aguiar; Unesp-Jaboticabal.
Os feijões estão entre os alimentos mais antigos, fazendo parte da alimentação diária da população brasileira. Objetivou-se com este trabalho determinar o período de convivência anterior à interferência das plantas daninhas (PAI) na cultura do feijoeiro em diferentes espaçamentos e densidades de plantas. Os tratamentos foram constituídos de períodos de convivência entre a cultura e as plantas daninhas, sendo zero a dez, zero a 20, zero a 30, zero a 40, zero a 50, zero a 60, zero a 70 e zero a 80 dias e mais uma testemunha sem convívio com as plantas daninhas. Além dos períodos de convivência, realizaram-se ainda estudos com espaçamentos entre linhas de 0,45 e 0,60 m e mais duas densidades de semeadura: dez e 15 plantas m-1. Adotou-se delineamento...
Palavras-chave: Phaseolus vulgaris; Competição; Períodos de controle Phaseolus vulgari; Competition; Control periods.
Ano: 2011
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/5646

Biological interactions in the co-occurrence of Eichhornia azurea and free-floating macrophytes - DOI: 10.4025/actascibiolsci.v31i4.5577
Provedor de dados: 3
Autores: Marques-Silva, Giuliani Grazyella; UEM; Thomaz, Sidinei Magela; UEM.
The dynamic of plant communities is strongly influenced by biological interactions. We studied the effects of Eichhornia azurea on the growth of the free-floating macrophytes Eichhornia crassipes, Salvinia minima, Salvinia auriculata and Limnobium laevigatum. The experiments were carried out in three lakes of the upper Paraná river floodplain. We used 0.5 m side squares where these species grew for 11 days (S. auriculata and L. laevigatum) and 17 days (E. crassipes and S. minima), in the presence and absence of E. azurea. There were no significant differences between the relative growth rates of macrophytes growing in the absence and presence of E. azurea. The relative interaction index showed the existence of competition between E. azurea and L....
Palavras-chave: 2.05.00.00-9 positive interactions; Free-floating macrophytes; Facilitation; Competition; Plant communities 2.05.00.00-9.
Ano: 2009
URL: http://periodicos.uem.br/ojs/index.php/ActaSciBiolSci/article/view/5577

Diet and niche breadth and overlap in fish communities within the area affected by an Amazonian reservoir (Amapá, Brazil)
Provedor de dados: 42
Autores: SÁ-OLIVEIRA,JÚLIO C.; ANGELINI,RONALDO; ISAAC-NAHUM,VICTORIA J.
We investigated the niche breadth and overlap of the fish species occurring in four environments affected by the Coaracy Nunes reservoir, in the Amapá Brazilian State. Seasonal samples of fishes were taken using a standard configuration of gillnets, as well as dragnets, lines, and cast­nets. Five hundred and forty stomach contents, representing 47 fish species were analyzed and quantified. Niche breadth and overlap were estimated using indexes of Levins and Pianka, respectively, while interspecific competition was evaluated using a null model (RA3). ANOVA and the Kruskal­Wallis test were used, respectively, to evaluate differences in niche breadth and overlap between areas. The data indicate that the majority of the fish species belong to the piscivore,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Neotropical reservoir; Diet; Species coexistence.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100383

One-eye-set sugarcane susceptibility to weed interference
Provedor de dados: 42
Autores: BELUCI,LUCAS R.; BACHA,ALLAN L.; BARROSO,ARTHUR A.M.; ALVES,PEDRO LUIS C.A.
Abstract The new technology of sugarcane planting, known as one-eye-set seedlings, offer a high standard of plant health and vegetative vigor. However, there are no reports in the literature that evaluate the weed competition with one-eye-set sugarcane seedlings, and the periods in which weed communities need to be controlled in this system. Two interference experiments were conducted in field conditions. The first experiment determined the periods of weed interference of an infesting community predominated by Ipomoea hederifolia and Merremia aegyptia in sugarcane. In the second experiment, these same species competed with plants of the same sugarcane cultivar. Productivity and qualitative aspects of production were evaluated. The critical period of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Critical period of interference prevention; Competition; Morning glory species; Periods of interference; Sugarcane OES.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000703513

Shoot and root interference of morning glory on the initial growth of sugarcane
Provedor de dados: 42
Autores: ALVES,FELIPE C.; BIANCO,SILVANO; NEPOMUCENO,MARILUCE P.; MARTINS,JOSÉ VALCIR F.; ALVES,PEDRO LUÍS C.A.
ABSTRACT Among weeds, morning glories comprise a very important group of climbing plants that infest sugarcane crops. The objective of this study was to evaluate the shoot and root interference of Merremia cissoides on the initial growth of sugarcane cultivar RB 966928. The experiment consisted of five treatment groups: (i) sugarcane monocropping, (ii) morning glory monocropping, (iii) sugarcane intertwined with morning glory but inseparate boxes, (iv) sugarcane intertwined with morning glory in attached boxes and (v) sugarcane with morning glory in attached boxes with morning glory prevented from intertwining with the sugarcane. The experimental design consisted of randomized blocks with four replicates. Merremia cissoides adversely affected the initial...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Merremia cissoides; Competition; Saccharum; Methodology.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000100521

Growth of tree species and sugarcane production in agroforestry systems
Provedor de dados: 42
Autores: CARON,BRAULIO O.; ELLI,ELVIS F.; BEHLING,ALEXANDRE; ELOY,ELDER; SCHMIDT,DENISE; STOLZLE,JOHN.
Abstract The appropriate choice of tree species and planting arrangement for use in agroforestry systems is very important in order to maximize productivity and sustainability. The aim of this study was to evaluate the growth of five tree species and its effect on sugarcane yields in different planting arrays in agroforestry systems. The study was conducted from 2007 to 2011 in the city of Frederico Westphalen, RS, Brazil. The five studied tree species were: guapuruvu (Schizolobium parahybae), bracatinga (Mimosa scabrella), canafístula (Peltophorum dubium), angico-vermelho (Parapiptadenia rigida) and eucalypt (Eucalyptus urophylla S.T. Blake x Eucalyptus grandis Hill ex Maiden). Root collar diameter, diameter at breast height, plant height and mean...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Array of plants; Competition; Crown diameter; Height.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000502425

Isotopic niches of sympatric native and exotic fish species in a Neotropical floodplain
Provedor de dados: 42
Autores: Philippsen,Juliana S.; Hauser,Marília; Benedito,Evanilde.
This study investigated the isotopic niches of two fish species, one exotic and one native. It was hypothesized that these species would show little or no isotopic niche overlap. This hypothesis was tested with the isotopic niche concept and the trophic Layman's metrics. A considerable isotopic niche overlap was observed between the species, mainly for the exotic that showed the greater percentage of overlapping, indicating an interspecific competition for food resources. Layman's metrics also showed this species probably exploits a more specific array of food resources when compared with the native species. The native species probably has the ability to exploit a wider array of resources, highlighted by the higher values given for the Layman's metrics....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Hoplias sp1; Hoplias sp2; Layman's metrics; Trophic interactions.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000200825

The classic episode of biological invasion: Cochliomyia macellaria (Fabricius, 1775) versus Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) - evaluation of the biotic potential
Provedor de dados: 42
Autores: BARBOSA,LEANDRO S.; COURI,MÁRCIA S.; COELHO,VALÉRIA M.A.; AVELINO-CAPISTRANO,FERNANDA.
ABSTRACT The classic episode of biological invasion: Cochliomyia macellaria (Fabricius, 1775) versus Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) - evaluation of the biotic potential. The biotic of the native fly Cochliomyia macellaria and the exotic Chrysomya megacephala was compared, through the reproductive capacity and longevity. The experiment took place in a climatized chamber, with four repetitions of 15 grouped couples of each species. The posture, egg mass weight, and death of individuals were observed daily. C. macellaria showed an average of longevity of 27.72 days while in C. megacephala the average was 41.96 days. The egg mass weight average per repetition was 0.58 g and 1.22 g, respectively. These results give a better...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Breed capacity; Longevity; Competition; Caliphorids.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000401401

Inhibition of iron and copper uptake by iron, copper and zinc
Provedor de dados: 48
Autores: ARREDONDO,MIGUEL; MARTÍNEZ,RONNY; NÚÑEZ,MARCO T; RUZ,MANUEL; OLIVARES,MANUEL.
Interactions of micronutrients can affect absorption and bioavailability of other nutrients by a number of mechanisms. In aqueous solutions, and at higher uptake levels, competition between elements with similar chemical characteristics and uptake process can take place. The consequences of these interactions may depend on the relative concentrations of the nutrients. In this work, we measure the effects of increasing concentrations of iron, zinc, and copper on iron and copper uptake in Caco-2 cells. Intracellular Fe or Cu levels were affected by incubating with increased concentrations of metals. However, when the cells already had different intracellular metal concentration, the uptake of Fe or Cu was nor affected. In competition studies, we showed that...
Tipo: Journal article
Palavras-chave: Competition; Interaction; Metals; Uptake.
Ano: 2006
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000100011

Effects of plant density and proportion on the interaction between wheat with alexandergrass plants
Provedor de dados: 53
Autores: Carvalho,Leonardo Bianco de; Alves,Pedro Luis da Costa Aguiar; Martins,José Valcir Fidelis.
Determination of competitive relationships among plant species requires appropriate experimental designs and method of analysis. The hypothesis of this research was that two species growing in coexistence show different growth and development due to their relative competitiveness. This research aims to measure the relative competitiveness of wheat crop compared to Alexandergrass by the interpretation of plant density and proportional effects using replacement series experiments. Monocultures were cultivated in densities of 1, 3, 5, 10 and 15 plants per pot and analyzed by regression of dry mass data. Mixture experiment was cultivated in wheat:Alexandergrass proportions of 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0 plants per pot and analyzed by graphical...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Brachiaria plantaginea; Triticum aestivum; Replacement series experiment.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052011000100007

Weed interference period and economic threshold level of ryegrass in wheat
Provedor de dados: 53
Autores: Galon,Leandro; Basso,Felipe José Menin; Chechi,Leonardo; Pilla,Thalita Pedrozo; Santin,Carlos Orestes; Bagnara,Maico André Michelon; Franceschetti,Milena Barretta; Castoldi,Camile Thaís; Perin,Gismael Francisco; Forte,César Tiago.
ABSTRACT The study of weed interference periods and the economic threshold level (ETL) of weeds on crops allows the adoption of management methods and the rationalized use of herbicides. The objective of this study was to determine the periods of interference and to test mathematical models to determine the economic threshold level of ryegrass in the wheat crop. Two experiments were carried out in a randomized block design with four replications. The first experiment was conducted in the 2014/2015 agricultural season. The periods of interference and control of ryegrass were studied in wheat. The periods of interference and/or control were: 0, 10, 20, 30, 40, 50 and 120 days after emergence (DAE). The second experiment was conducted in the 2016/2017...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Triticum aestivum; Lolium multiflorum; Competition.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052019000300409

Relative competitiveness of soybean cultivars with barnyardgrass
Provedor de dados: 53
Autores: Bastiani,Marlon Ouriques; Lamego,Fabiane Pinto; Agostinetto,Dirceu; Langaro,Ana Claudia; Silva,Diônvera Coelho da.
ABSTRACT The aim of this work was to evaluate the competitiveness between soybean cultivars and barnyardgrass, based on morphological and physiological characteristics of species. The experiments were conducted in completely randomized experimental design, with 4 replications. In the first study, for both soybean and barnyardgrass, it was determined the population of plants in which shoot dry matter became constant and independent of the population (16 plants∙pot−1 or 400 plants∙m−2). In the second study, 2 experiments were conducted to evaluate the competitiveness of BMX Apolo RR and BMX Potência RR soybean cultivars with barnyardgrass plants, both carried out in replacement series under different proportions of plants∙pot−1 (100:0; 75:25; 50:50; 25:75...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Echinochloa crus-galli; Lowlands; Replacement series; Competition.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052016000400435

The abiotic environment of Heliamphora nutans (Sarraceniaceae): pedological and microclimatic observations on Roraima Tepui
Provedor de dados: 52
Autores: Adlassnig,Wolfram; Pranji,Kornelija; Mayer,Edith; Steinhauser,Georg; Hejjas,Flora; Lichtscheidl,Irene K.
The aim of this study was the study of the abiotic environment of the carnivorous pitcher plant Heliamphora nutans (Sarraceniaceae), including the microclimate and the geochemistry of the soil of the growing sites on Roraima Tepui and discuss their relevance within the recent model of carnivorous plant ecology. The soil was peaty and low in nutrients. The microclimate on the site was very balanced, with moderately cool temperatures, a constant high humidity and very low wind speed. Heliamphora was not exposed to any recognizable climatic stress. Previous macroclimatic measurements reflected the growth conditions of Heliamphora only incorrectly, since humidity decreased drastically with height. The apparent conflict with the common model of carnivorous...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carnivorous plants; Microclimate; Soil; Niching; Competition; Cultivation.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132010000200022

COMPETITIVE ABILITY OF WHEAT IN ASSOCIATION WITH BIOTYPES OF Raphanus raphanistrum L. RESISTANT AND SUSCEPTIBLE TO ALS-INHIBITOR HERBICIDES
Provedor de dados: 64
Autores: Costa,Leandro Oliveira da; Rizzardi,Mauro Antônio.
The occurrence of Raphanus raphanistrum ALS herbicide-resistant in wheat crops causes crop yield losses, which makes it necessary to understand the factors that influence the interference of this weed to develop safer management strategies. This study aimed to evaluate the competitive ability of wheat in coexistence with biotypes of R. raphanistrum that are resistant (R biotype) and susceptible (S biotypes) to ALS herbicides and to determine whether there are differences in the competitiveness of these biotypes. The experiments were conducted in a greenhouse using a completely randomized design with four replications. The treatments were placed in pots and arranged in replacement series for three experiments (1 - wheat with the R biotype; 2 - wheat with...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Resistance; Competition; Replacement series.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542015000200121

Weed interference periods in sesame crop
Provedor de dados: 64
Autores: Lins,Hamurábi Anizio; Souza,Matheus de Freitas; Albuquerque,José Ricardo Tavares de; Santos,Manoel Galdino dos; Barros Júnior,Aurélio Paes; Silva,Daniel Valadão.
ABSTRACT The sesame crop (Sesamum indicum L.) is sensitive to competition with weeds because of its low competitiveness that is directly linked to its slow initial growth. The control of weeds in the crop is an essential practice to ensure the high productivity of this oilseed. Therefore, to define the critical period of interference prevention is important to ensure efficiency and low control costs. Factors such as cultivar, environmental conditions, and cultivation system may alter the critical weed interference prevention period (CPWC). Therefore, the objective of this work was to determine the critical weed interference prevention period in two sesame cultivars. The critical weed interference prevention period for sesame cultivars, BRS Seda and CNPA...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Competition; Leaf area; Plant height; Productivity; Oilseeds.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542019000100220

Interference of soybean and corn with Chloris distichophylla
Provedor de dados: 64
Autores: Wandscheer,Alana Cristina Dorneles; Rizzardi,Mauro Antônio.
In nature, plants interact with each other and establish positive, negative, and neutral interference relationships. In agricultural ecosystems, crops are usually affected by competition with weeds, and the effects of this process are influenced by the plant population density and proportional abundance and by the species involved. The present study evaluates the competitive interactions of soybean and corn with Chloris distichophylla. Two experiments were conducted in a greenhouse belonging to the University of Passo Fundo during the 2011/12 crop season: one experiment involving corn and C. distichophylla and another involving soybean and C. distichophylla. The experimental units were plastic pots, and the treatments were based on a replacement series,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Weeping fingergrass; Competition; Crops.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542013000400003