The ecological stability, plasticity, and genetic determinants of maize ( Zea mays L.) performance under drought-prone conditions of the Ukrainian Steppe

This study evaluated maize (Zea mays L.) breeding material for ecological plasticity and stability under the arid conditions of the Ukrainian Steppe and characterized the genotypes using cleaved amplified polymorphic sequence (CAPS) molecular markers associated with drought tolerance. Four agronomic and morphological traits ‒ grain yield, grain moisture content, plant height, and ear height ‒ were evaluated across contrasting years. Year-specific weather conditions had the strongest effect on all traits, whereas the effects of genotype and genotype × year interactions were less pronounced but statistically significant. Several maize genotypes exhibited high ecological plasticity (b) combined with low ecovalence (W), indicating their potential for high yield and favorable agronomic performance under favorable growing conditions. Genotype No. 17 (RL412S/RL746mS/LP9) showed high potential responsiveness to improved growing conditions for grain yield, plant height, and ear height. Genotypes No. 63 (RL255S/RL74mS/8141) and No. 164 (RL413S/RL255mS/PR3R86) showed high potential responsiveness to improved growing conditions for reducing grain moisture at harvest but limited adaptability for plant height. Molecular analysis identified genotypes carrying favorable allele combinations associated with drought tolerance. Lines LP9 and LP15, in suitable tester combinations, combined high adaptability for grain yield with favorable dhn1 and rsp41 alleles. Additionally, genotypes involving lines LP12, 680, and 44 showed a relatively conservative response pattern and limited potential responsiveness to improved growing conditions, but maintained stable trait expression and drought resilience despite lower productivity, highlighting their value for stress-oriented breeding programs.