Articles

Genetic analysis of grain yield performance and weevil [Sitophilus zeamais (Motschulsky)] resistance in southern African maize hybrids


Abstract


Maize (Zea mays L) grain losses due to grain weevils threaten food security in poor rural communities where grain is stored on farm without any chemical treatment in developing countries. Progress in developing high-yielding and weevil-resistant maize varieties is scarcely reported in the literature. Knowledge of the mode of inheritance for both grain yield and weevil resistance in elite maize germplasm would be crucial in designing viable breeding strategies. Therefore hybrids that were generated in a North Carolina design II mating scheme were evaluated for grain yield over three environments. Hybrids were also evaluated for maize weevil (Sitophilus zeamais Motsch) resistance under controlled temperature and relative humidity in the laboratory. Results revealed that only a few hybrids combined high grain yield potential and maize weevil-resistance reflecting the challenges which may be encountered in developing productive hybrids. However, highly significant differences between hybrids for both grain yield and weevil resistance indicated opportunities for selection. Furthermore, weevil resistance was found in at least four major heterotic groups suggesting that development of weevil-resistant hybrids could be created by crossing complementary lines from these heterotic groups. Significance of GCA and SCA effects suggested that genes with both additive and non-additive effects, respectively, were important for grain yield. The SCA effects were not significant (P > 0.05) for grain weevil resistance parameters, suggesting that genes with additive effects played a predominant role in governing the resistance in hybrids. Generally the baseline resistance to maize weevil could be improved through selection, while procedures that emphasize both GCA and SCA would be exploited to enhance grain yield in this set of maize germplasm.

Keywords

maize, combining ability, maize weevil, resistance, post-harvest losses

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