Field Response and Genetic Variability Analyses of Maize (Zea mays L.) Hybrids and Commercial Varieties Under Natural Fall Armyworm (Spodoptera frugiperda (J. E. Smith)) Infestation in Lowland Tropical Ecology

Maize response to fall armyworm

Abstract

Fall armyworm (Spodoptera frugiperda (J.E. Smith)) (FAW) impacts maize (Zea mays L.) production. No maize genotype is completely resistant to FAW. This experiment was conducted in Calabar, Cross River State, with twenty maize genotypes using a randomised complete block design with three replications. FAW scores, plant height, leaf count, plant aspect rating, days to 50% anthesis and silking, anthesis-silking interval, fresh and de-husked cob weight and length, husk proportion, ear aspect rating, grains per cob, 100-seed weight, and grain yield responses were all different. FAW score perfectly correlated with plant and ear aspect ratings. Grain yield strongly associated with cobs per plant and grains per cob. The analysis of genetic variability revealed that while seedling emergence, days to 50% anthesis, and 50% silking exhibited moderate genetic advance, all other traits demonstrated high genetic advance, indicating the potential for selecting maize genotypes for these traits under FAW pressure. FAW score, plant aspect, and ear aspect were all found to be in the same cluster in the principal component and genotype by traits biplot analyses. This proved that they were useful for identification of maize genotypes that are tolerant to FAW pressure. In one cluster were cobs per plant, husk covering, cob length, and grains per cob with grain yield. This further confirmed the importance of these traits in selecting maize genotypes with high yield potential under FAW pressure. Despite FAW pressure, maize genotypes AS2001-20, AS2001-24, M1628-8, AS2106-63, and FAW 2212 demonstrated high grain yields considerable for inclusion in further FAW-related studies.