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| Registros recuperados: 28 | |
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| Brieger,F. G.. |
| 1) The first part deals with the different processes which may complicate Mendelian segregation and which may be classified into three groups, according to BRIEGER (1937b) : a) Instability of genes, b) Abnormal segregation due to distur- bances during the meiotic divisions, c) obscured segregation, after a perfectly normal meiosis, caused by elimination or during the gonophase (gametophyte in higher plants), or during zygophase (sporophyte). Without entering into detail, it is emphasized that all the above mentioned complications in the segregation of some genes may be caused by the action of other genes. Thus in maize, the instability of the Al factor is observed only when the gene dt is presente in the homozygous conditions (RHOADES 1938). In another... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761945000100009 |
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| Brieger,F. G.. |
| The main object of the present paper consists in giving formulas and methods which enable us to determine the minimum number of repetitions or of individuals necessary to garantee some extent the success of an experiment. The theoretical basis of all processes consists essentially in the following. Knowing the frequency of the desired p and of the non desired ovents q we may calculate the frequency of all possi- ble combinations, to be expected in n repetitions, by expanding the binomium (p-+q)n. Determining which of these combinations we want to avoid we calculate their total frequency, selecting the value of the exponent n of the binomium in such a way that this total frequency is equal or smaller than the accepted limit of precision n/pª{ 1/n1 (q/p)n +... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1947 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761947000100012 |
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| Brieger,F. G.. |
| Na aplicação do X2-teste devemos distinguir dois casos : Á) Quando as classes de variáveis são caracterizadas por freqüências esperadas entre p = 0,1 e p = 0,9, podemos aplicar o X2-teste praticamente sem restrição. É talvez aconselhável, mas não absolutamente necessário limitar o teste aos casos nos quais a freqüência esperada é pelo menos igual a 5. e porisso incluimos na Táboa II os limites da variação de dois binômios ( 1/2 + 1/2)n ( 1/4 + 3/4)n para valo r es pequenos de N e nos três limites convencionais de precisão : ,5%, 1% e 0,1%. Neste caso, os valores dos X2 Índividuais têm apenas valor limitado e devemos sempre tomar em consideração principalmente o X2 total. O valor para cada X2 individual pode ser calculado porqualquer das expressôe... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1948 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761948000100002 |
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| Brieger,F. G.. |
| 1) Chamamos um desvio relativo simples o quociente de um desvio, isto é, de uma diferença entre uma variável e sua média ou outro valor ideal, e o seu erro standard. D= v-v/ δ ou D = v-v2/δ Num desvio composto nós reunimos vários desvios de acordo com a equação: D = + Σ (v - 2)²: o o = o1/ o o Todo desvio relativo é caracterizado por dois graus de liberdade (número de variáveis livres) que indicam de quantas observações foi calculado o numerador (grau de liberdade nf1 ou simplesmente n2) e o denominador (grau de liberdade nf2 ou simplesmente n2). 2) Explicamos em detalhe que a chamada distribuição normal ou de OAUSS é apenas um caso especial que nós encontramos quando o erro standard do dividendo do desvio relativo é calculado de um número bem grande de... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761945000100011 |
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| Brieger,F. G.. |
| The object of the present paper is a study of the usefulness of two relative measures of variation, the well known coefficient oj variation and a new term proposed in this paper and called the index of variance. These terms are defined by the equations : coefficient of variation : σ% = s /v/v. 100 index of variance :σ/ √. 1. It is shown that, for theoretical reasons, only the index of variance may be expected to be constant. Six different experimental series actually proved this constancy, showing at the same time the variability of the coefficient of variation which proved to be dependent upon the respective mean. The coefficient of variation becomes approximately constant when the respective means are sufficiently distant from the absolute limit zero or... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1942 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051942000900001 |
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| Brieger,F. G.. |
| The experiments reported were started as early as 1933, when indications were found in class material that the factor for small pollen, spl, causes not only differences in the size of pollen grains and in the growth of pollen tubes, but also a competition between megaspores, as first observed by RENNER (1921) in Oenothera. Dr. P. C. MANGELSDORF, who had kindly furnished the original seeds, was informed and the final publication delayed untill his publication in 1940. A further delay was caused by other circunstances. The main reason for the differences of the results obtained by SINGLETON and MANGELSDORF (1940) and those reported here, seems to be the way the material was analysed. I applied methods of a detailed statistical analysis, while MANGELSDORF and... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761945000100008 |
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| Brieger,F. G.; Lima,A. Rodrigues; Forster,R.. |
| 1) The object of the experiment presented in this publication was a detailed comparison between progenies of the varieties Virginia and Sumatra of the collection of the Instituto Agronômico de Campinas. We intended to decide whether these strains were sufficiently heterogeneous to permit further selections or whether they were already so uniform as to allow a reduction in their number within our collection. 2) A preliminary experiment in 1939/40 showed clearly that some of the 7 types introduced as Sumatra were less resistant than others, and the experiment was thus continued "with only four of them. 3) The lay-out of the final experiment was such as to permit both a complete analysis of soil heterogeneity and of differences between the genetically... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1942 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051942000800001 |
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| Brieger,F. G.. |
| 1) Inicialmente foi dado um breve resumo dos métodos básicos do melhoramento no milho os quais podem ser reunidos em dois grupos principais: o processo do milho híbrido, com as suas variantes, e os processos dos sintéticos. Estes últimos podem ainda ser subdivididos em duas categorias: os sintéticos simples e os sintéticos balançados. Na obtenção dos sintéticos simples toma-se inicialmente em consideração a capacidade combinatória das linhagens a serem misturadas, e se executa em cada geração de sintético uma seleção massal de conservação. Nos balançados devemos acrescentar uma forte seleção, na fase preparatória, contra todos os híbridos que dão segregações mendelianas fortes demais. 2) No curso de um breve resumo histórico ficou evidente que a idéia de... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1951 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761951000100031 |
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| Brieger,F. G.. |
| O presente trabalho não tem por fim discutir exaustivamente os fatos conhecidos e as hipóteses até hoje formuladas sobre o mecanismo da evolução. Êle apresenta apenas um resumo de alguns pontos, sem entrar numa discussão detalhada da literatura, com o fim de por em relevo principalmente os métodos como podem aparecer expontaneamente novos caracteres. As nossas considerações servem como uma introdução para alguns trabalhos experimentais, que serão publicados a seguir. A) - Conhecemos até agora os seguintes modos para a obtenção de novos caracteres fenotipos: 1) - Mutação gênica. 2) - Alteração citológica como poliploidia, polisomia e aberrações na estrutura cromossômica. 3) - Recombinação gênica, ou pela combinação de efeitos específicos de gens... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1944 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761944000100009 |
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| Brieger,F. G.. |
| 1) O equilíbrio em populações, inicialmente compostas de vários genotipos depende essencialmente de três fatores: a modalidade de reprodução e a relativa viabilidade e fertilidade dos genotipos, e as freqüências iniciais. 2) Temos que distinguir a) reprodução por cruzamento livre quando qualquer indivíduo da população pode ser cruzado com qualquer outro; b) reprodução por autofecundação, quando cada indivíduo é reproduzido por uma autofecundação; c) finalmente a reprodução mista, isto é, os casos intermediários onde os indivíduos são em parte cruzados, em parte autofecundados. 3) Populações heterozigotas para um par de gens e sem seleção. Em populações com reprodução cruzada se estabelece na primeira geração um equilíbrio entre os três genotipos, segundo a... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1948 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761948000100003 |
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| Brieger,F. G.; Lima,A. Rodrigues; Forster,R.; Costa,A. S.; Santos,S. Ribeiro dos. |
| 1. Since our experiments on tobacco during the past years were greatly prejudiced by the extreme effect of the infection by the virus of the "vira-cabeça" causing the death of the great majority of the plants attacked, it was considered necessary to carry out an extensive experiment in order to determine whether there are differences: between localities, between varieties, between times of planting. Thus the experiment was carried out during 3 years in four Experiment Stations in the State of São Paulo: (Campinas, Piracicaba, Tietê e Limeira). In the first year 10 varieties were included and later on their number was reduced to 6. It was planed to sow and plant at regular time intervals and simultaneously in all Exp. Sta's, but this turned out to be... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1942 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051942000800002 |
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| Brieger,F. G.; Moreira,Silvio; Leme,Z.. |
| 1. The present paper represents the final report of the experiment about the constancy in a clon of the orange "Baianinha" which has been studied during the past four years. 2. The trees were obtained by grafting buds taken from one tree, 17-2, of the "Asilo" in Piracicaba, on non-selected seedling root stock of sour orange. 3. The fruits were collected separately for each tree and their diameter (in mm) determined. The test "within-between" showed clearly that the variation between the means of trees and within trees are of a totally different order, the former being about 10 times bigger than the latter. 4. Thus it was necessary to use other tests in order to be able to find out whether the trees form a uniform sample or not. A X²-test was carried out... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1941 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051941000800002 |
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| Brieger,F. G.. |
| 1) It may seem rather strange that, in spite of the efforts of a considerable number of scientists, the problem of the origin of indian corn or maize still has remained an open question. There are no fossil remains or archaeological relics except those which are quite identical with types still existing. (Fig. 1). The main difficulty in finding the wild ancestor- which may still exist - results from the fact that it has been somewhat difficult to decide what it should be like and also where to look for it. 2) There is no need to discuss the literature since an excellent review has recently been published by MANGELSDORF and REEVES (1939). It may be sufficient to state that there are basically two hypotheses, that of ST. HILAIRE (1829) who considered... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1944 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761944000100011 |
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| Brieger,F. G.. |
| The study of pod corn seems still of much importance from different points of view. The phylogenetical importance of the tunicate factor as a wild type relic gene has been recently discussed in much detail by MANGELSDORF and REEVES (1939), and by BRIEGER (1943, 1944a e b). Selection experiments have shown that the pleiotropic effect of the Tu factor can be modified very extensively (BRIEGER 1944a) and some of the forms thus obtained permitt comparison of male and female inflorescences in corn and related grasses. A detailed discussion of the botanical aspect shall be given shortly. The genetic apect, finally, is the subject of the present publication. Pod corn has been obtained twice: São Paulo Pod Corn and Bolivia Pod Corn. The former came from one half... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761945000100007 |
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| Brieger,F. G.. |
| 1) The present paper deals with variations in the structure of the inflorescences of the Maydeae Americanae, especially of the ear of Zea Mays, which came under observation during our genetical studies during the last 10 years. Care was tauken to include only such structures which were observed frequently and had in general an aspect which could not be described as a pathological abnormality, but rather as a reversion to a phylogenetically primitive type or as a new form. The aberrations may be summarized as follows: a) Individual flowers. Eeversion to the hermaphrodite state of the usually unisexual flowers in Maydeae were described. Such flowers are however already so well known that no details need to be given. b) Many flowered spikelets. The spikelet... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051945001100001 |
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| Brieger,F. G.; Moreira,Sílvio. |
| The English resumé is given in a different form from the Portuguese "conclusões". In the former we gave mainly the results which may be of general interest, explaining the tables (quadros) and the procedure of statistical analysis, while in the other the properties of the different rootstocks are discussed in detail since they are of immediate local interest. 1. In a previous publication, Moreira (19) explained the layout and the first results of an experiment, under way since 1936 in the Limeira Exp. Sta., on the influence of twelve different types of Citrus rootstocks on three scion varieties : the oranges "Baianinha" and "Pera" and the grape-fruit "Marsh Seedless". We report here three main results obtained during the first six years of the experiment:... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1945 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051945001000001 |
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| Brieger,F. G.; Gurgel,J. T. A.. |
| 1 - The object of the present paper is the study of the effect of different rootstocks on pollen fertility of the scion. The material was obtained from experiments by Moreira (18), in progress at the Experimental Station, Limeira, São Paulo, and from experiments by Vasconcelos (1), in progress in the Experimental Orchard at Piracicaba, São Paulo. Homogeneity test of method 2 -A preliminary homogeneity test was carried out and showed that the methods for collecting and counting pollen were sufficiently satisfactory. This test consisted in the following : pollen was collected from 3 plants for each of 5 different rootstocks, budded with laranja pera and for each plant 3 determinations were made. The decomposition of the total error showed no significant,... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1941 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051941001000002 |
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| Brieger,F. G.. |
| Preliminary studies on brazilian orchid species show that the existing material offers the possibility for studying the following general questions: a) In spite of the rule about the relative proportion between numbers of individuals per species and number of species per unit area in tropical and in temperate zones, the orchid genera seem to follow more closely the rule of temperate zone species, and this in spite of the fact that the family is undoubtedly of tropical origin. b) The large amont of paralell variation existing between different genera recquires a detailed explanation, and extensive introgressive hybridization is mentioned as one possibility. c) The existence of natural sympatric hybrids, both inter-generic and interspecific, and the... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1951 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0071-12761951000100032 |
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| Registros recuperados: 28 | |
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