Abstract
This experimental study investigates the physiological and molecular responses of maize (Zea mays L.) under drought stress conditions using controlled greenhouse experiments. A total of 90 maize plants were exposed to three irrigation regimes representing 100%, 60%, and 40% field capacity over a 60-day growth period to evaluate drought-induced effects on plant performance. Key growth and physiological parameters including plant height, biomass accumulation, chlorophyll content, and stomatal conductance were analyzed alongside the expression of drought-responsive genes DREB2A and NAC1. The results revealed significant reductions in plant height (−32%) and biomass accumulation (−41%) under severe drought stress conditions (p < 0.001), indicating the substantial negative impact of water deficiency on maize growth and productivity. However, drought-tolerant genotypes maintained significantly higher chlorophyll content (SPAD value: 42.3 ± 2.1) compared with susceptible varieties (31.7 ± 1.8), demonstrating enhanced physiological adaptability under stress conditions. Gene expression analysis further revealed a 3.5-fold upregulation of DREB2A in tolerant plants, highlighting the important role of molecular defense mechanisms in drought adaptation. The findings emphasize the integrated contribution of physiological and genetic responses in improving crop resilience under climate stress. This study provides valuable insights for the development of climate-resilient maize cultivars and supports the integration of plant science innovations into sustainable agricultural systems to mitigate the adverse impacts of climate change