Genetic analysis of grain yield and adaptive traits in provitamin A maize hybrids under combined drought heat stress and well‐watered conditions

One hundred and fifty‐four three‐way cross maize ( Zea mays L.) hybrids generated from a line × tester mating design were evaluated together with eight commercial checks for tolerance to combined drought and heat stresses. The experiment was conducted in a 9 × 18 alpha (0.1) lattice design replicated twice across 10 different environments. The aim of the study was to evaluate International Maize and Wheat Improvement Center and International Institute of Tropical Agriculture provitamin A maize doubled haploid and elite inbred lines for their combining ability, gene action, and inter‐trait relationships for grain yield and adaptive traits. Analysis of variance for grain yield and most traits showed significant differences at p ≤ 0.05 for general combining ability and specific combining ability (SCA) effects signifying the influence of additive and nonadditive effects. Line × tester variance components for grain yield and most traits were higher compared to line and tester variances signifying predominance of additive effects. Inbred lines DS197‐47 and TZMI2104 were strongest general combiners. A cross between TZMI2031‐2 × CLHP0237/CML304 had highest SCA effects under optimum conditions, while inbred line DS197‐217 crossed to CLHP0237/CML304 had highest SCA effects under stressed conditions. Under both conditions, grain yield was positively correlated with ears per plant and plant height while negatively correlated to ear aspect, anthesis date, and kernel texture. Recurrent selection can be employed to accumulate favorable alleles of secondary traits, while hybridization can be used to exploit heterosis for grain yield under combined drought and heat stress. The findings of this research provide a strong foundation for the development of resilient and high‐yielding provitamin A maize hybrid.