Coronatine Improves Water Productivity of Maize (Zea mays L.) Under Deficient Irrigation in Northwest Arid Region of China

Maize (Zea mays L.) production and yield are threatened by water deficit in the arid and semiarid areas of China. Improving water productivity (WP_c) through innovative approaches is crucial for developing water-saving agricultural systems. Coronatine (COR) is a natural phytotoxin known to elicit plant resistance responses to biotic and abiotic stress. The aim of this study was to evaluate the effect of COR in alleviating the adverse effects of drought stress on maize growth and development. A field experiment with four treatments (I100, water applied under normal irrigation; I50, water applied under deficit irrigation; I50-0.1, 0.1 μmol L⁻¹ COR applied under deficit irrigation; I50-1.0, 1.0 μmol L⁻¹ COR applied under deficit irrigation) was implemented in the arid regions of northwest China. The results showed that deficit irrigation reduced the 2-year average yield by 10.8%. Under drought conditions, COR enhanced drought tolerance by sustaining photosynthetic efficiency, ultimately improving WP_c and yield in maize. Notably, COR application at 1.0 μmol L⁻¹ demonstrated superior efficacy in enhancing drought tolerance compared to other concentrations. The maize plants treated with 1.0 μmol L⁻¹ COR improved the 2-year average yield by 6.0% and WP_c by 17.9%, and decreased evapotranspiration by 10.0% compared to untreated control plants under deficit irrigation. These results highlight COR's potential as a water-saving agrochemical for semi-arid maize cultivation, providing a viable strategy to balance yield maintenance with limited water resources.