Genetic control of traits associated with maize seed quality

Abstract

The aim of this work was to estimate genetic parameters for traits associated with maize seed quality of two populations in an interpopulational recurrent selection for this trait. Two populations derived from singlecross commercial hybrids and currently in Hardy-Weinberg equilibrium (1 and 2) were used for these experiments. Initially 169 half-sib progenies were obtained from each population. All progenies were sown in two isolated fields. The pollinator from one field was population 1 and the pollinator was the opposite population on the other field, all developed under similar conditions. The ears harvested by hand, in both isolated fields were bulked, resulting in a “half-sib progeny bulk”. This seed production method produced an adequate quantity of same-ageseed of each intra and inter progenies to use in the seed quality tests. The seed produced was initially separated using screens and were evaluated seeds of the same size in the germination test (GT), speed of germination index (SGI) and the accelerated aging test (AAT). Each plot consisted of 25 seeds and the design was completely randomized (one way classification) with four replications. The genetic and phenotypic parameters were estimated based on the mean square expectations of variance and covariance analyses. The populations of intra and interpopulational half-sibs differed in seed quality. The heterosis estimates were of low magnitude 4.5% in the GT, 10.1% in the AAT and 5.7% in the SGI. The largest proportion of the interpopulational additive genetic variance (σ 2 A12 or σ 2 A21) was explained by the intrapopulational additive variance (σ 2 A11 or σ 2 A22). This indicates the lesser importance of dominance and that reciprocal recurrent selection is less efficient than intrapopulational selection for these traits.