Heterose entre linhagens de soja quanto aos teores de proteína e de óleo no grão
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2006-03-23
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Universidade Federal de Goiás
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The soybean (Glycine max (L.) Merrill) is one of the most important grain cultivated in the world, mainly because its high levels of grain protein and oil, and also due to its high yield. Soybean protein has become an important product in the food and feed industries, due to its nutritional value and technological properties. Agricultural business increasingly demands specific quality traits, creating the need for developing types of productive soybean, with high levels of protein and oil in the grain. Information about the genetic divergence among genitors allows the breeder to select that ones potentially able to generate greater variability, increasing the probability of getting superior genotypes in segregating generations. The purpose of this study was to evaluate inbred lines of soybean and its hybrids based on grain protein and oil content. The heterosis and its components were used as indicators for the genitors potential to generate by crossing segregating genotypes for these traits. Eighteen genitors and its hybrid combinations were evaluated to grain protein and oil content, in a partial diallel arrangement. The genitors were classified in two groups based on their flower color (white and purple) allowing us to detect the effective crosses. Physicochemical analyses were made in grains of F1 plants obtained in a green house. The Kjeldahl and Soxhlet methods were used to determine protein and oil content, respectively. The mean squares from the analysis of variance of the diallel model were significant (P<0.05) for all sources of variation based on the grain protein and oil contents, except for the genitor heterosis effect in the group 1 (white) for protein content. The groups of genitors presented distinct means for both protein and oil contents, with highest values for group 2 (purple). The presence of genetic variability shows that the selection of genotypes with greater contents of grain protein and oil can be effective in the final phase of a soybean breeding program. The significance of heterosis effect showed the presence of dominance in the loci that control grain protein and oil contents, allowing the use of genitors for the formation of promissory segregant population. The average heterosis were negative, so the hybrid means are significantly smaller than that of the genitors. This shows that genitors have gene frequencies sufficiently different at least in part of the loci with dominance effects, with the prevalence of dominant alleles that contribute to the decrease of contents for both traits. Genitors showed to be heterogeneous in their heterotic contribution to the formation of hybrids, except for protein content in the group 1. The significance of specific heterosis showed that the genitors of each group are sufficiently different in order to cause gene complementation in the dominant loci for protein and oil contents. The presence of genetic divergence allows the selection of parental inbred lines for use in breeding programs using hybridization methods, with the goal of gathering alleles that are favorable to the increase of grain protein and oil content. For the evaluated genotypes, it can be concluded that the additive and non-additive gene effects are important in the determination of the contents of grain protein and oil
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RIBEIRO, Keyla de Oliveira. Heterosis among inbred lines of soybean based on the grain protein and oil contents. 2006. 69 f. Dissertação (Mestrado em Ciências Agrárias) - Universidade Federal de Goiás, Goiânia, 2006.