Genetic variability, heritability, and yield performance of maize genotypes evaluated across highland environments

Maize is a crucial cereal crop for food security in Ethiopia; however, its productivity is constrained by low-yielding varieties and various stresses. This study evaluated 48 F₁ single-cross hybrids along with two commercial checks across two highland locations employing an alpha lattice design with two replications. Combined analysis of variance showed significant genotypic variations for most traits and significant genotype × location interaction for grain yield and selected agronomic traits. Grain yield ranged from 4.64 to 10.17 t ha − 1 , with some hybrids showing a yield advantage of more than 10% over the best check. GGE biplot analysis preliminarily identified G21, G29, and G15 as high-yielding and relatively stable genotypes across the two tested environments, although it requires validation across additional location and seasons. These genotypes were provided yield advantages of 22.10%, 16.30%, and 15.70%, respectively. Genotypes G45, G27, and G19 showed specific adaptation to Holeta, while G21, G44, and G17 performed best at Ambo. Many of superior-performing hybrids involved tester FS59, indicating that this tester was frequently associated with favorable hybrid performance. Broad-sense heritability ranged from 23.6% to 90.9%, with ear height exhibiting high heritability and genetic advance as a percentage of the mean (21.07%), indicating clear genetic differentiation among hybrids. Grain yield exhibited positive and significant genotypic correlations with plant height (r g = 0.486**), ear height (r g = 0.335**), and ear per plant (r g = 0.586**), supporting their use as indirect selection criteria. Overall, the identified high-yielding and stable hybrids can be advanced to national trials following multi-location and season testing, while superior inbred lines should be utilized in future breeding programs targeting Ethiopian highland environments.