Genotype by environment interaction analysis for fall armyworm (Spodoptera frugiperda) response and yield stability of maize hybrids (Zea maize L.) in southern Ethiopia

Abstract This study lies in the simultaneous evaluation of maize hybrids for grain yield stability and FAW tolerance under natural infestation conditions in the Gamo lowlands, an area where such integrated assessments are limited. The study also provides valuable insights into the magnitude and pattern of GEI effects under FAW pressure and identifies promising hybrids with broad adaptation and stable performance across environments to enhance maize productivity and resilience in the region. Therefore, the study aimed to evaluate genotype × environment interaction (GEI) for yield stability and the response of maize hybrids to FAW infestation under natural field conditions in southern Ethiopia. The experiment was conducted at two locations, Gamo Development Farm and Shelle, around Arba Minch area during the 2022 and 2023 main cropping seasons using thirty-two maize hybrids, including the standard check BH-546, in a 4 × 8 alpha lattice design with three replications. Combined analysis of variance revealed significant ( P < 0.05) differences among genotypes, environments, and GEI effects for several traits. The GEI effect contributed substantially to the total variation observed in FAW scores, husk cover, and phenological traits, indicating differential hybrid responses across environments. Grain yield variation was primarily attributed to genotypic and environmental effects, highlighting the importance of both genetic potential and environmental conditions in hybrid performance. AS200119 and AS200121 combined high yield (up to 75% over check) with low FAW scores, indicating potential dual-purpose selection for productivity and pest tolerance. AS200119 and AS200121 also showed consistent and stable performance for grain yield and FAW tolerance, demonstrating their potential for enhancing maize productivity in the target environments. The genotype plus genotype-by-environment (GGE) contributed 73.8% for grain yield and 76.8% for FAW score, whereas environment 3 (AM23) and environment 4 (SH23) were the most representative environments to test both traits. Overall, the findings highlight AS200119 and AS200121 as potential candidate hybrids for future maize improvement and dissemination in southern Ethiopia and similar agro-ecologies.