Response of summer maize growth, water use and yield to staged deficitirrigation in the seasonally arid regions of Southwest China

Understanding drought response mechanisms is critical for high-efficiency maize produc-tion in the seasonally arid regions of Southwest China. A two-year field experiment(2022–2023) was conducted using a randomized block design with two deficit degrees(D25% and D50%) imposed at single or multi stages to investigate summer maize growth,yield and water use responses to stage-specific deficit irrigation (DI). The study site islocated in a typical seasonally arid region with subtropical climate. Results indicated thatDI during vegetative growth (VG) period significantly inhibited maize morpho-physiological traits (p < 0.05) but triggered compensatory recovery after reirrigation, andenhanced instantaneous water use efficiency and grain dry matter proportion (7.75%–12.52% higher than CK). Conversely, DI during reproductive growth (RG) period markedlydecreased grain yield and protein content. DI at VG and early RG period also effectivelyincreased starch content by 2.38%-15.78%. Moreover, deficit degree and stage generallysignificantly affected maize morpho-physiological traits, dry matter, yield and quality (p <0.05). Entropy-TOPSIS evaluation identified the D25% treatment at seedling stage as theoptimal strategy, as it maintained yield stability (4.52% reduction, p > 0.05) while enhan-cing water use efficiency (3.26%). We conclude that stage-specific DI serves as a practical, climate-adaptive tool for summer maize production i nseasonally aris regions.