Heterosis and genetic parameters for yield and nutritional components in half-sibling maize progenies
The growing demand for maize creates a challenge for breeders; they need to constantly develop higher yielding and higher quality genotypes. We estimated the most relevant genetic parameters, along with heterosis and variance components. A multivariate approach was used in order to define profiles of narrow sense heritability for yield and nutritional components in half-sibling maize progenies. The applied experimental design was random blocks with a male parent (hybrid tester), five inbred lines (S5) as maternal parents and the progenies (hybrid Top Cross), totaling 11 maize genotypes arranged in six replicates. Agronomic and nutritional characters were evaluated. Half-sibling progenies revealed greater additive genetic contribution to phenotypic expression with grain width and thickness, iron content, total flavonoids and carotenoids, soluble solids, and methionine. Narrow sense heritability values between and within progenies were higher for manganese content, glycine, proline and tryptophan. Regardless of the S5 inbreeding line used, heterosis gains were obtained for ear insertion height, number of grain rows per ear, stalk diameter, zinc content, total carotenoids, soluble solids and pH. Specific heterosis was found for grain yield, glycine, serine, threonine and phenylalanine. The multivariate analysis defined eight profiles of traits according to their genetic tendencies, and indicated narrow sense heritability of the progeny mean as the main reason for this classification.