Targeted adaptation options can effectively reduce amplified compound water-heat stress around maize flowering in China

Compound water and heat stresses cause great crop yield losses, threatening food security. However, the current extent and future trajectory of these stresses remain uncertain. Here, we developed a compound water-heat stress index (WHSI) to quantify the spatiotemporal variations in co-occurring water and heat stresses around maize flowering in China. We demonstrated that WHSI can effectively capture historical yield variations in major maize-growing regions. Future projections show a substantial increase in compound water-heat stress events, particularly in northeast and northwest of China, driven primarily by rising temperature. By optimizing planting dates and selecting suitable cultivars, compound water-heat stress can be alleviated by more than 70% through dynamic adaptation (site- and year-specific adjustments), representing a potential upper bound of adaptation under the strategies considered. These results highlight the critical role of targeted adaptation measures implemented to mitigate the worsening impact of amplified compound water-heat stress on crop yield. Dynamic adaptation through optimized planting dates and cultivar selection can reduce compound water–heat stress impacts on maize by over 70% in China, despite intensifying climate stresses, based on a newly developed stress index and climate-driven projections.