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Search Results: 1 - 10 of 81337 matches for " Carlos Tadeu dos Santos;Vencovsky "
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Controle genético da regenera??o in vitro em progênies de Eucalyptus grandis
Bravo, Carlos David Vera;Gon?alves, Ant?nio Natal;Dias, Carlos Tadeu dos Santos;Vencovsky, Roland;
Ciência Rural , 2008, DOI: 10.1590/S0103-84782008000800014
Abstract: the genetic control of in vitro direct regeneration was tested on seedlings of ten open-pollinated progenies from the base population of atherton origin of eucalyptus grandis at university of s?o paulo (brazil). seeds were germinated in vitro, after twenty days, distal hypocotyls segments from 196 seedlings per progeny were inoculated in culture media at generalized complete randomized block design, with two experimental units per block and seven repetitions, using the interaction blocks by progenies as an estimate of the experimental error. at week 14 from the inoculation bud induction was evaluated. regeneration among progenies were significantly different (p<0.0001). regeneration varied from 11 to 60%. the narrow-sense heritability between means of experimental units for in vitro regeneration was height. (h2m=0.94), indicating a strong genetic control of the trait within the population and also a high maternal effect. high variability within the study sample was found.
Estimadores de componentes de variancia em delineamento de blocos aumentados com tratamentos novos de uma ou mais popula??es
Duarte, Jo?o Batista;Vencovsky, Roland;Dias, Carlos Tadeu dos Santos;
Pesquisa Agropecuária Brasileira , 2001, DOI: 10.1590/S0100-204X2001000900009
Abstract: this work compares by simulation estimates of variance components produced by the anova (analysis of variance), ml (maximum likelihood), reml (restricted maximum likelihood), and mivque(0) (minimum variance quadratic unbiased estimator) methods for augmented block design with additional treatments (progenies) stemming from one or more origins (crosses). results showed the superiority of the mivque(0) estimation. the anova method, although unbiased, showed estimates with lower precision. the ml and reml methods produced downwards biased estimates for error variance (), and upwards biased estimates for genotypic variances (), particularly the ml method. biases for the reml estimation became negligible when progenies were derived from a single cross, and experiments were of larger size with ratios />0.5. this method, however, provided the worst estimates for genotypic variances when progenies were derived from several crosses and the experiments were of small size (n<120 observations).
Estimadores de componentes de variancia em delineamento de blocos aumentados com tratamentos novos de uma ou mais popula es
Duarte Jo?o Batista,Vencovsky Roland,Dias Carlos Tadeu dos Santos
Pesquisa Agropecuária Brasileira , 2001,
Abstract: O objetivo do trabalho foi comparar, por meio de simula o, as estimativas de componentes de variancia produzidas pelos métodos ANOVA (análise da variancia), ML (máxima verossimilhan a), REML (máxima verossimilhan a restrita) e MIVQUE(0) (estimador quadrático n o viesado de variancia mínima), no delineamento de blocos aumentados com tratamentos adicionais (progênies) de uma ou mais procedências (cruzamentos). Os resultados indicaram superioridade relativa do método MIVQUE(0). O método ANOVA, embora n o tendencioso, apresentou as estimativas de menor precis o. Os métodos de máxima verossimilhan a, sobretudo ML, tenderam a subestimar a variancia do erro experimental () e a superestimar as variancias genotípicas (), em especial nos experimentos de menor tamanho (n<120 observa es). Quando as progênies vieram de um só cruzamento, REML praticamente perdeu estes vícios nos experimentos maiores e com raz es />0,5. Contudo, o método produziu as piores estimativas de variancias genotípicas quando as progênies vieram de diferentes cruzamentos e os experimentos foram pequenos.
Predicting performance of soybean populations using genetic distances estimated with RAPD markers
Barroso, Paulo Augusto Vianna;Geraldi, Isaias Olívio;Vieira, Maria Lúcia Carneiro;Pulcinelli, Carlos Eduardo;Vencovsky, Roland;Dias, Carlos Tadeu dos Santos;
Genetics and Molecular Biology , 2003, DOI: 10.1590/S1415-47572003000300020
Abstract: in order to verify whether genetic distance (gd) is associated with population mean (pm), genetic variance (gv) and the proportion of superior progenies generated by each cross in advanced generations of selfing (ps), the genetic distances between eight soybean lines (five adapted and three non-adapted) were estimated using 213 polymorphic rapd markers. the genetic distances were partitioned according to griffing's model i method 4 for diallel analysis, i.e., gdij = gd+ ggdi+ ggdj + sgdij. phenotypic data were recorded for seed yield and plant height for 25 out of 28 populations of a diallel set derived from the eight soybean lines and evaluated from f2:8 to f2:11 generations. no significant correlation for seed yield was detected between gd and gv, while negative correlations were detected between gd and pm and between gd and ps (r = -0.74** and -0.75**, respectively). similar results were observed for the correlation between ggdi + ggdj and pm and between ggdi + ggdj and ps (r = -0.78** and -0.80**, respectively). no significant correlation was detected for plant height. the magnitudes of the correlations for seed yield were high enough to allow predictions of the potential of the populations based on rapd markers.
Utiliza??o de técnicas estatísticas em duas revistas de fruticultura
Cantuarias-Avilés, Tatiana;Dias, Carlos Tadeu dos Santos;
Ciência Rural , 2008, DOI: 10.1590/S0103-84782008000800044
Abstract: the statistical techniques and statistical accessibility were analyzed in a sample collected from the original articles published between 1996 and 2006 by two fruticulture journals: the revista brasileira de fruticultura (rbf) and the french journal fruits. a total of 986 original articles were classified in 16 classes of statistical analyses, previously ordered by increasing degree of complexity. the complexity of statistical techniques used by both journals increased in time. along the 1996-2006 period, the articles published in the rbf journal utilized more complex statistical techniques, as well as experimental designs in randomized blocks, factorial, split plot and hierarchical arrangements, and the test of tukey for mean comparisons. in the articles published by the fruits journal the use of other parametrical tests and the duncan test was more frequent. in both journals the sas statistical software was most frequently utilized. readers of the rbf journal required a higher level of statistical knowledge to understand the techniques utilized in the articles.
Análise AMMI com dados imputados em experimentos de intera??o genótipo x ambiente de algod?o
Arciniegas-Alarcón, Sergio;Dias, Carlos Tadeu dos Santos;
Pesquisa Agropecuária Brasileira , 2009, DOI: 10.1590/S0100-204X2009001100004
Abstract: the objective of this work was to evaluate the convenience of defining the number of multiplicative components of additive main effect and multiplicative interaction models (ammi) in genotype x enviroment interaction experiments in cotton with imputed or unbalanced data. a simulation study was carried out based on a matrix of real seed-cotton productivity data obtained in trials with genotype x environment interaction carried out with 15 genotypes at 27 locations in brazil. the simulation was made with random withdrawals of 10, 20 and 30% of the data. the optimal number of multiplicative components for the ammi model was determined using the cornelius test and the likelihood ratio test onto the matrix completed by imputation. a correction based on the data missing in the cornelius procedure was proposed for testing the hypothesis when the analysis is made from averages and the repetitions are not available. for data imputation, the methods considered used robust submodels, alternating least squares and multiple imputation. for analysis of unbalanced experiments, it is advisable to choose the number of multiplicative components of the ammi model only from the observed information and to make the classical estimation of parameters based on the matrices completed by imputation.
Acurácia do modelo univariado para análise de medidas repetidas por simula??o multidimensional
Xavier, Lara Hoffmann;Dias, Carlos Tadeu dos Santos;
Scientia Agricola , 2001, DOI: 10.1590/S0103-90162001000200005
Abstract: in experiments using repeated measurements, when split plot designs are utilized the f test in relation to the subplot will have an exact f distribution only if the matrix of covariance satisfies the sphericity condition. the objective of this article was to verify throught simulation the accuracy of the analysis throught the observation of some cases when the matrix of covariance satisfies or not the sphericity condition. when the matrix of covariance was of the component type of variance and of compound symmetry, the sphericity condition was satisfied and the accuracy of the analysis adequate. this does not happen with other structures of the covariance matrix. in relation to the effects of parameters, depending on the magnitude of the values of the effects, they will interfere with the results of the tests, over estimating the effects when the amplitude of the effects is large.
Choosing components in the additive main effect and multiplicative interaction (AMMI) models
Dias, Carlos Tadeu dos Santos;Krzanowski, Wojtek Janusz;
Scientia Agricola , 2006, DOI: 10.1590/S0103-90162006000200009
Abstract: the additive main effect and multiplicative interaction (ammi) models allows analysts to detect interactions between rows and columns in a two-way table. however, there are many methods proposed in the literature to determine the number of multiplicative components to include in the ammi model. these methods typically give different results for any particular data set, so the user needs some guidance as to which methods to use. in this paper we compare four commonly used methods using simulated data based on real experiments, and provide some general recommendations.
Análise e quantifica??o do risco para a gest?o eficiente do portfólio agrícola das seguradoras
Ozaki, Vitor Augusto;Dias, Carlos Tadeu dos Santos;
Revista de Economia e Sociologia Rural , 2009, DOI: 10.1590/S0103-20032009000300001
Abstract: in the agricultural insurance, the presence of adverse events can compromise the financial health of the agricultural insurance companies. drought, for example, can affect not only one producer, but thousand of producers in a huge territorial extension. to skirt this problem, insurance companies diversify geographically their operations. this paper applies the cluster analysis in a corn yield data set for the regions of paraná state, considering the period from 1990 to 2005. in total, 39 groups were formed according to similar characteristics of expected yield and relative risk. based on one of insurability criteria, some high-risk regions were excluded, and groups were classified according to the degree of relative risk.
HARVEST TIME AND PHYSIOLOGIC QUALITY OF SEEDS IN IRRIGATED RICE (Oryza sativa cv. BRS RORAIMA) éPOCA DE COLHEITA E QUALIDADE FISIOLóGICA DE SEMENTES EM ARROZ IRRIGADO (Oryza sativa cv. BRS RORAIMA)
Oscar José Smiderle,Carlos Tadeu dos Santos Dias
Pesquisa Agropecuária Tropical , 2008, DOI: 10.5216/pat.v38i3.3487
Abstract: Harvest time is one of most important factors influencing rice seed characteristics for purpose of either planting or milling. With the objective to determine a proper harvesting time, irrigated rice seeds of cultivar BRS Roraima were harvested at 15, 22, 29, 36, 43 and 50 days after flowering (DAF), and assessed according to humidity, viability, dry mass of 1,000 seeds, whole grain yield, productivity and storability. Seeds harvested 29 DAF showed high quality and its productivity was equivalent to the subsequent periods. Seeds harvested 50 DAF showed good performance, except for whole grain yield. Harvests 15 and 22 DAF were unsuitable, reducing the physiologic quality of seeds, mill efficiency and high initial humidity. The adequate harvest time for cultivar BRS Roraima is between 29 and 43 DAF, when seeds present higher yield, dry mass, whole grain yield, physiologic quality and storability. KEY-WORDS: Physiologic quality; whole grain; humidity. A época de colheita é um dos fatores mais importantes que influenciam as características da semente de arroz, seja para semeadura ou para consumo. Com o objetivo de determinar a época adequada de colheita de arroz irrigado, para a cultivar BRS Roraima, sementes foram colhidas aos 15, 22, 29, 36, 43 e 50 dias após o florescimento (DAF) e avaliadas quanto à umidade, viabilidade, massa seca de 1.000 sementes, rendimento de gr os inteiros, produtividade e armazenabilidade. As sementes colhidas aos 29 DAF tiveram alta qualidade e a produtividade foi equivalente à dos períodos subseqüentes. Aquelas provenientes da colheita aos 50 DAF exibiram bom desempenho, exceto em rendimento de gr os inteiros. Colheitas realizadas aos 15 e 22 DAF s o impróprias, reduzindo a qualidade fisiológica das sementes, o rendimento de engenho e a alta umidade inicial. A época adequada de colheita para a cultivar BRS Roraima está entre 29 e 43 DAF, quando suas sementes apresentam maior produtividade, massa seca, rendimento de gr os inteiros, qualidade fisiológica e armazenabilidade. PALAVRAS-CHAVE: Qualidade fisiológica; gr os inteiros, umidade.
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