Melhoramento genético e biometria aplicada a produtividade e biofortificação de grãos de milho

Abstract

The genetic breeding of maize is dynamic and requires a multidisciplinary comprehension from the breeder, ability to plan and execute agronomic activities, crosses, selections, applicability of biometric models, obtaining of productive genotypes and biofortified grains. The objectives of the present work were: 1) To estimate the variance components and genetic parameters (REML), the linear phenotypic, genetic, environmental and canonical correlations for the traits of agronomic interest in maize; 2) To identify the linear, cause and effect associations between traits, and the stability by Annicchiarico´s method of the crude protein of maize grains cultivated in four different environments; 3) To determine the linear associations, to estimate genetic parameters and heterosis of bioactive compounds and micronutrients in maize intervarietal hybrids; 4) To estimate heterosis, components of variance and the most relevant genetic parameters, to use a multivariate approach to define narrow sense heritability profiles for yield and nutritional components in maize half-sibling progenies; 5) To estimate the variance components and genetic parameters (REML/BLUP) of an intervarietal diallel, to select and predict the best genotypes for maize yield components. The main conclusions were: 1) the greatest contribution of genetic variation in the genotypes x environments interaction and broad sense heritability was verified for spike diameter, number of rows in the ear, and cob diameter; 2) the increase of plant height, mass of a thousand grains and grain yield reduces crude protein content in maize grain; 3) the thickness and color of the seeds, total phenols, antioxidant radical by ABTS and zinc content are increased through the effects of intervarietal heterosis; 4) the narrow sense heritability among and within the progenies are superior for manganese, glycine, proline and tryptophan content in maize grains; 5) male genitors and the additive genetic fraction are determinant to the grain volume relative index, however, the mass of one hundred grains and grain yield are determined by the intervarietal specific combining ability.