Análise dialélica, estimativas de parâmetros genéticos e fenotípicos e seleção de genótipos de soja para a produção de grãos e precocidade

Abstract

The study of the inheritance of agronomic traits and the selection of the most effective methods are fundamental in breeding programs for the development of new soybean cultivars. This thesis was subdivided into two chapters. The first aimed to estimate the general and specific combining abilities of six soybean parents through a partial diallel, with the goal of identifying the most promising genotypes for agronomic traits and the best combinations for developing superior lines. Fifteen hybrid combinations, without reciprocals, and six parents (UFUS7101, UFUS8401, UFUS7201, UFUS7910, UFUS 7010, and BRS511) were analyzed through the partial diallel proposed by Geraldi and Miranda Filho (1988). From the diallel analysis, it can be concluded that the parents BRS 511 and UFUS7010 stood out in terms of earliness, and the parent UFUS8401 for its yield potential. The combination UFUS7101 x UFUS8401 proved to be promising for obtaining early populations with high yield potential. The second chapter aimed to analyze the inheritance of agronomic traits in the segregating F2 and F2:3 generations and their parents, SYN1163 RR and UFUS7415. The agronomic traits evaluated were: number of days to flowering, plant height at flowering, number of days to maturity, plant height at maturity, first pod height, total number of nodes, number of productive nodes, number of branched nodes, number of pods with 1, 2, and 3 seeds, total number of pods, grain yield per plant, and grain yield per row. The estimates of heritability and minimum number of genes evidenced the quantitative nature of the agronomic traits, particularly for grain yield per plant in the F2 generation. Furthermore, the presence of transgressive individuals for most of the traits evaluated was observed, enabling the selection of superior individuals. In the F2:3 generation, distinct groups of means for the studied traits were formed, and there was a high selection gain for both selection indices used: the Genotype-Ideotype distance and the sum of ranks by Mulamba & Mock (1978).