Avaliação de progênies S0:1 de milho visando grãos de textura farinácea e produtividade

Abstract

Maize (Zea mays L.) is one of the most important crop used as energy concentrate for animal nutrition. In Brazil, most maize hybrids have hard endosperm (flint or vitreous) with low starch digestibility. Therefore, it is important to carry out breeding programs with focus on high yield and decreasing the proportion of vitreous endosperm of grains. The objective of this study was to estimate genetic and phenotypic parameters associated with S0:1 progenies derived from temperate germplasm, estimate selection gain achieved for characteristics related to vitreousness and yield using a selection index for multiple characters and select progenies with lower vitreousness and high yield. The experiments were conducted at Centro de Desenvolvimento Científico e Tecnológico of the Universidade Federal de Lavras (UFLA), in Lavras, Minas Gerais. In 2016/2017 crop season the S0:1 progenies were evaluated in a 17x17 triple square lattice design (287 progenies + BM 3061 and 20A78 controls) and in the 2017/2018 a 8x8 triple lattice (64 progenies + BM 3061 and 3066 controls) was adopted. The characteristics evaluated were vitreousness and yield components: ear weight, grain weight, length of total grains per row (obtained from the number of rows of grains (NFG) x number of grains per row (NGF). In 2016/2017 season, the indentation score and weight of dehusked ears were evaluated, and the grain density was evaluated in 2017/2018. Genetic and phenotypic parameters, genotype correlations, correlated response, expected gain with the selection made by the index were estimated. The frequency distribution graphs of the adjusted means and the graphical representation of the performance of the six best and worst progenies were obtained considering the Z index. Variance components proved the existence of variability among the progenies, suggesting that it is possible to select superior genotypes. The selection index based on the characters VITLUZ, DENS, PE and PG, provided expressive gains and proportional distribution for all the characters. Progenies 260, 212, 232, 200, 230 and 6 presented better estimates of gains for all the characters referring to vitreousness and grain yield and are promising for the continuity of the breeding program.