Soil-plant-environment informed deficit drip irrigation enhances maize yield and resource-use efficiency

Increasing water scarcity and rainfall variability under climate change are major constraints to sustainable crop production in dryland agricultural systems, highlighting the need for irrigation strategies that not only adapt to changing climates but also improve grain yield (GY) and resource-use efficiency. Here, we developed a Soil–Plant–Environment informed Irrigation (SPEI) framework and evaluated it in a seven-year (2014–2020) maize ( Zea mays L. ) field experiment in northwest China. Treatments included rainfed (RF), conventional flood irrigation (CK), SPEI-guided full drip irrigation (FI) and deficit drip irrigation (DI, 75% of FI). SPEI parameterizes irrigation quota by soil water-holding capacity in the drip-wetted root zone and triggered irrigation using accumulated crop evapotranspiration combined with short-term rainfall forecasts. The results showed that SPEI-guided drip irrigation (DI and FI) increased water retention in the 0–60 cm root zone and reduced deep percolation and nitrate-N leaching by 19.8–65.6%. These improvements were accompanied by enhanced canopy function (higher leaf area index and chlorophyll content) and improved gas exchange and stress-adjustment traits, which promoted post-anthesis dry matter accumulation and ultimately increased GY. Across years, DI increased GY by 9.6%, water productivity by 25.8%, and nitrogen productivity by 21.7% relative to CK, while showing no significant GY penalty compared with FI. This was likely because DI induced a mild stress response (higher abscisic acid (ABA), superoxide dismutase and proline) and an ABA-linked stomatal adjustment that reduced transpiration. Structural equation modeling showed that canopy traits, dry matter accumulation/translocation, and yield components jointly explained > 90% of the variation in GY. Overall, SPEI-guided deficit drip irrigation offers a practical, climate-resilient pathway to maintain maize yield while enhancing water-nitrogen use efficiency and reducing environmental losses under increasing hydroclimatic variability. • A Soil–Plant–Environment informed drip irrigation (SPEI) framework was proposed. • Deficit irrigation under SPEI improves maize yield by 9.6% and water use efficiency by 25.8%. • Soil processes and crop drought-resistance traits under SPEI jointly enhance productivity. • The framework offers scalable, climate-resilient irrigation strategies for dryland farming.