Consulta: creatorFacets:"Lehmann, M. F."
Registros recuperados: 2
Data/hora: 14/06/2024 09:16:21

A mid-Holocene transition in the nitrogen dynamics of the western equatorial Pacific: Evidence of a deepening thermocline?
Provedor de dados: 5
Autores: Kienast, M.; Lehmann, M. F.; Timmermann, A.; Galbraith, E.; Bolliet, T.; Holboum, A.; Normandeau, C.; Laj, C.
Sedimentary delta(15)N records from the oligotrophic western equatorial Pacific (WEP) off Mindanao show that late Holocene sedimentary delta(15)N is substantially lower than that of the early Holocene, following a gradual &gt;3 parts per thousand decrease that occurred between 7 and 3 kyrs ago. Analyses of modem day nitrate isotope profiles from the same region indicate the sensitivity of the WEP N pools towards (1) the advection of (15)N-enriched nitrate from the Eastern Equatorial Pacific (EEP) by the North Equatorial Current (NEC) and the Mindanao Current in subsurface waters and, (2) at shallow depths, the input of new and (15)N-depleted nitrate through N, fixation. We suggest that the Holocene decrease in sedimentary delta(15)N reflects a diminished...
Tipo: Text
Palavras-chave: Tropical Pacific; El Nino; Surface temperature; Fresh water; Nitrate; Mindanao; Ocean; Variability; Holocene; Seawater.
Ano: 2008
URL: https://archimer.ifremer.fr/doc/00207/31843/30257.pdf

Effects of two contrasted arbuscular mycorrhizal fungal isolates on nutrient uptake by Sorghum bicolor under drought
Provedor de dados: 21
Autores: Symanczik, S.; Lehmann, M. F.; Wiemken, A.; Boller, T.; Courty, P. E.
Drought is a limiting factor for crop production, especially in arid and semi-arid climates. In this study, Sorghum bicolor plants were inoculated, or not, with Rhizophagus irregularis, an arbuscular mycorrhizal (AM) strain typical for temperate climates, or Rhizophagus arabicus, a strain endemic to hyper-arid ecosystems. Plants were grown under well-watered or drought conditions in compartmented microcosms. Transpiration rates, plant growth, and nutrient uptake (using 15N as a tracer) were determined to assess the impact of drought stress on sorghum plants in AM symbiosis. Although AM colonization did not affect the bulk biomass of host plants, R. arabicus improved their transpiration efficiency and drought tolerance more than R. irregularis. Moreover, R....
Tipo: Journal paper
Palavras-chave: Soil biology.
Ano: 2018
URL: http://orgprints.org/34760/1/symanczik-etal-2018_mycorrhiza-Vol28_Issue8-p779-785.pdf