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

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 randomized complete block design with three replications. These maize genotypes varied in responses to FAW scores, plant height, leaf count, plant standability and performance, days to 50% anthesis and silking, anthesis-silking interval, fresh and de-husked cob weight and length, husk proportion, ear rating, grains per cob, 100-seed weight, and grain yield. FAW score perfectly correlated with plant and ear ratings. Grain yield is strongly associated with cobs per plant and grains per cob. The study of this genetic variability showed that while seedling emergence, days to 50% anthesis, and 50% silking showed moderate genetic gain, all other traits showed high genetic gain. This suggests that under FAW pressure, it might be possible to choose maize genotypes that have these traits. FAW score, plant standability and performance, and ear rating 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 the 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.