Genotype and environmental effects on grain yield, agronomic performance, and beta-carotene content of provitamin a maize in tropical savannah ecologies

Provitamin A (PVA) biofortified maize, with elevated beta-carotene (a vitamin A precursor), offers a sustainable strategy for reducing vitamin A deficiency (VAD) in maize-based diets. However, its grain yield, agronomic performance, and beta-carotene stability across diverse environments must be understood to guide effective variety selection and deployment. This study assessed genotype, environment, and genotype x environment (GxE) interaction effects on grain yield, agronomic performance, and beta-carotene content of five extra-early PVA maize hybrids evaluated across six rainfed environments in the Guinea and Sudan Savannah zones of Ghana (2020-2021). Environmental effects were highly significant for grain yield and most agronomic traits, while genotypic and GxE effects were significant for several traits but not for grain yield. Mean grain yield was 3.77 t/ha, and EEPVAH/19/91, EEPVAH/19/59, and EEPVAH/19/53 out-yielded the non-biofortified local check by 21.8-24.9%, indicating no yield penalty from biofortification. Broad-sense heritability ranged from low to high, with grain yield showing moderate heritability (H 2 = 0.56), supporting selection for genetic gain. Grain yield was strongly associated with most heritable traits, including ears harvested per plot, root and stalk lodging, and ear height. Beta-carotene content of the hybrids ranged from 1.40 to 18.26 μg/g with significant genotype, environment, and GxE effects. A multiple-trait selection index identified EEPVAH/19/59 (18.26 μg/g; 4.04 t/ha), EEPVAH/19/91 (2.80 μg/g; 4.06 t/ha), and EEPVAH/19/53 (7.75 μg/g; 3.96 t/ha) for nutrition-led, broadly adapted, and risk-prone rainfed deployment, respectively. These findings provide valuable guidance for breeding, selection, and targeted deployment of PVA maize hybrids in VAD-prone regions. • Grain yield and most agronomic traits were strongly influenced by environmental and genotypic effects • Grain yield also showed strong negative genetic and phenotypic correlations with flowering time, anthesis–silking interval, lodging, and ear aspect • Beta-carotene content varied significantly with genotype, environment, and genotype x environment interaction, with two hybrids surpassing the best local check in beta-carotene content. • Provide valuable guidance for breeding, selection, and targeted deployment of PVA maize hybrids in VAD-prone regions