Formation of Heterotic Groups and Understanding Genetic Effects in a Provitamin A Biofortified Maize Breeding Program

Abstract

Developing biofortified maize (Zea mays L.) cultivars is a viable approach to combating the widespread problem of vitamin A deficiency among people for whom maize is a staple food. To enhance CIMMYT’s provitamin A maize breeding efforts, this study: evaluated whether separation of experimental maize lines into groups based on maximizing their molecular-marker-based genetic distances (GD) resulted in heterosis for among-group crosses, assessed genetic effects (general and specific combining ability, GCA and SCA) for grain yield and provitamin A concentrations in hybrids among 21 inbred lines representing the three proposed groups assessed the association between grain yield and provitamin A concentrations. The lines were crossed following a partial diallel design resulting in 156 hybrids that were evaluated at four environments with two replications of one-row plots. The first plant in each plot was self-pollinated to produce grain for provitamin A analysis. Significant but small yield advantage of among- versus within-group crosses (0.47 Mg ha−1, P