Drought stress is a major constraint in maize (Zea mays L.) production that significantly affects grain yield. Maize hybrids with broad adaptation and environment-specific potential related to water stress will ensure sustainable maize production. The presented study aimed to evaluate the grain yield performance of eight hybrids and two commercial check cultivars of maize under irrigated and drought-stress conditions and the correlation among tolerance indices and identify the stable and high-yielding hybrids. The study was conducted in four different environments, with two each under irrigated and drought-stress conditions, using a randomized complete block design with three replications. Maize genotypes, environments, and genotype-by-environment interactions (GEI) significantly (P < 0.01) affected grain yield. Hybrids experienced a 42.4% yield reduction under drought compared with irrigated conditions. The tolerance indices mean productivity (MP), harmonic mean (HM), geometric mean productivity (GMP), stress tolerance index (STI), yield index (YI), and modified stress tolerance index (K1STI and K2STI) showed significant correlations with grain yield under both environments. Based on the tolerance indices, the drought-tolerant hybrids that included G05 (R0641), G03 (R0211), and G08 (R0020) performed better. GGE biplot analysis identified two mega-environments, where the G06 emerged superior under irrigated conditions and G03 under drought stress, while G05 was stable under both environments.

Keywords: Maize (Z. mays L.), drought stress, genotype-by-environment interaction, hybrid selection, multi-environment trial, tolerance indices

Key findings: Drought stress significantly reduced the grain yield of maize (Z. mays L.) and can worsen with increased drought intensity, highlighting the critical need for drought-tolerant hybrids in tropical agriculture. Tolerance indices and GGE biplot can explain the strengths and weaknesses in identifying the drought-tolerant maize hybrids.