Variation in the phenotypic performance of top-cross fall armyworm resistant maize hybrids under optimal growing conditions in a derived savanna agro-ecology

Fall armyworm ( Spodoptera frugiperda ) severely threatens sustainable maize production in smallholder farming systems across sub-Saharan Africa. Developing maize hybrids resistant to fall armyworm with high grain yield can enhance productivity and stability, especially in the savanna agro-ecology. This study aimed to identify such resistant hybrids, assess their genetic variability, heritability, and trait relationships under natural infestation and disease pressure. Thirty-two (32) maize hybrids, including commercial checks, were evaluated at two sites on the Teaching and Research farm of Ladoke Akintola University of Technology, Ogbomoso, Nigeria, in an 8 × 4 α-lattice design with three replications. Combined analysis of variance revealed highly significant (p < 0.001) differences among hybrids, environments, and hybrid × environment interactions for grain yield and other agronomic traits. Significant genetic variation for grain yield, foliar diseases, fall armyworm damage, ear rot, and related traits across sites suggests potential for selecting superior resistant hybrids. Approximately 30.7% of tested hybrids outperformed the highest yielding check (G31: Oba Super 9). Hybrid G1 (FAWSYN-1/(TZLComp.1 C6-W-39-1-1)-B-B) had the highest grain yield of 5223.3 kg ha⁻¹, showing a 26.8% yield advantage over the top check. Phenotypic correlations showed grain yield was negatively and significantly (p < 0.001) associated with fall armyworm foliar damage, plant aspect, and husk cover ratings. Regression analyses emphasized plant aspect as the strongest contributor to grain yield. In stepwise regression, fall armyworm infestation had significant detrimental effects (p < 0.01) on grain yield, husk cover, and ear and plant aspect ratings. Genotype by grain yield × trait (GYT) biplot identified five hybrids (G1, G9, G21, G18, and G3) that combined high yield, moderate fall armyworm resistance, and stability across environments. These promising hybrids are recommended for multilocational yield trials aiming to release fall armyworm resistant, high-yielding maize varieties suited for the derived savanna agro-ecology.