Desempenho de híbridos de milho e capacidade combinatória para escolha de genitores e classificação de grupos heteróticos

Abstract

Combining ability plays a crucial role for indicating most potential genotypes for crossing, gene effects acting in the phenotype and provides insights on how to enhance germplasm heterotic response and breeding efficiency. Regarding to this, the objectives of my research were: i) to evaluate parentals of maize to further inbreds extraction; ii) to classificate a set of progenies derived from commercial hybrids into heterotic groups; and iii) to evaluate the performance of maize hybrids for cultivars development. In view of these purposes, a partial diallel was conducted between a group of eleven testers, belonging to two known heterotic groups of maize, which come from the reciprocal recurrent selection program of UFLA, and ten progenies derived from commercial hybrids of maize, which heterotic groups were unknown. The single crosses were evaluated in field trials at the first and second corn season of 2018/19. All trials were located at the region of Lavras-MG, Brazil, and planted following lattice design with three replications. REML/BLUP based analysis was done to evaluate the combining ability of parentals and performance of hybrids for traits grain yield, disease severity, number of kernels per ear and 100-kernel weight. The diallel-based analysis revealed that non-additive effects were more important to grain yield, whereas primarily additive effects were more important to all other traits. Furthermore, there were identified promising parents for traits grain yield and 100-kernel weight at both seasons; and for number of kernels per ear at first season, therefore, they were best for obtaining populations to further inbreds extraction. However, no crosses were found for parental selection for trait disease severity. On the other hand, there were identified promising hybrids with high grain yield and good resistance to disease at both seasons, thus, they were best for cultivars development. All progenies derived from commercial hybrids of maize were classified into two heterotic groups.