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ResumoO estudo quantitativo de diferentes características agronômicas é importante em programas de melhoramento de plantas. Todavia, a estimativa de parâmetros genéticos relacionados à qualidade fisiológica de sementes tem sido pouco explorada, com escassez de informações na literatura. O objetivo deste trabalho foi estimar parâmetros genéticos da qualidade fisiológica de sementes de três cultivares e quatorze linhagens de soja, com ciclo de maturação tardio, que participaram de cinco ensaios finais de avaliação de linhagens, do Programa de Melhoramento Genético de Soja do Departamento de Fitotecnia da UFV. Os ensaios foram conduzidos em Tupaciguara, Florestal, Unaí e dois locais em Capinópolis, no estado de Minas Gerais, no ano agrícola 2000/2001. O delineamento experimental utilizado foi em blocos ao acaso com três repetições. A qualidade fisiológica das sementes foi avaliada pelo teste de germinação e de emergência de plântulas em leito de areia. Os parâmetros genéticos estimados foram componente quadrático genotípico, componente de variância genótipos x ambientes, coeficiente de determinação genotípico, coeficiente de variação genético. A germinação das sementes das cultivares FT 104, Doko-RC e Conquista e das linhagens UFV97-61190916 e UFV98-CR67 foi maior que 85% em todos os ambientes. Os coeficientes de determinação genotípico, obtidos a partir dos dados de germinação de sementes e de emergência de plântulas, variaram entre ambientes. A seleção individual de genótipos de soja, com base na qualidade fisiológica das sementes por local, pode propiciar maiores ganhos quando comparado à seleção em que se consideram todos os ambientes conjuntamente. Palavras-chave: Glycine max, coeficiente de determinação genotípico, coeficiente de variação genético, genética da soja AbstractThe quantitative study of different agronomic characteristics is of great importance in plant breeding programs. However the estimation of genetic parameters related to seed physiologic quality has been little explored and works of that are scarec in the literature. The objective in this work was to estimate genetic parameters for seed physiologic quality of three soybean cultivars and fourteen lineages, with late maturation cycle, that are part of five final experiments of lineages evaluation from the Program of Genetic Improvement of Soybean of the Department of Fitotecnia of UFV, led in Tupaciguara, Florestal, Unaí and two places in Capinopolis, state of Minas Gerais, in the agricultural year 2000/2001. The

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The aim of this study was to evaluate the diversity of phenotypic and molecular traits in soybean cultivars launched in forty years of breeding. The DNA was amplified with 42 microsatellite markers (SSR). Polymorphisms of 38 SSR markers were identified in polyacrylamide gel at 10%. 106 alleles were amplified with an average of 2.52 alleles per SSR locus. Polymorphism information content varied from 0 to 0.68 with an average of 0.38. Genetic dissimilarities between pairs of cultivars varied from 0.4 to 0.6, 0.8 to 1.0 and 0.0 to 0.4 for data obtained from SSR markers, coefficient of parentage and phenotypic characters, respectively. It was possible to verify the contribution of cultivars considered old, intermediate and recent as well as the genetic variability of the group of cultivars used, which remained the same over 40 years of breeding. It was also observed that, with the combination of six microsatellite primers, it was possible to distinguish the 21 cultivars used in this study; and that microsatellite markers showed less biased estimates compared to the estimates obtained by the parentage coefficient and phenotypic characters in studies on genetic diversity.

With the aim of studying the relationship between the physiological quality of soybean seeds submitted to three harvest times and seedling emergence in the field, seeds of cultivars UFV-16, Splendor, Vencedora, Confiança, UFV-18, UFV-TN 105, Garantia and Celeste were harvested at stages R8, R8+15 and R8+30 days. The following tests were performed: accelerated aging, electrical conductivity, emergence in sand, emergence speed index and seedling emergence in the field. Germination and vigor were reduced in seeds harvested at 30 days after stage R8 in all the tests, except for the accelerated aging test, which showed a decline in vigor seeds harvested with a delay of 15 days. Seeds of cultivars UFV-16, Confiança and Garantia showed lower physiological quality in most tests, while the seeds of cultivar Celeste had higher physiological quality than the others. There was similarity between the test results of seed quality and seedling emergence in the field.