Impact of water deficit and irrigation management on winter wheat yield in China

Increasing scarcity of irrigation water is threatening global winter wheat production and food security. As a major world food crop, irrigation has been pivotal in enhancing the sustainable production of wheat. To ensure food and water security, it is vital to better understand wheat irrigation demands during key growth periods to improve water productivity (WP). Here we combined precipitation and crop water requirements to analyze the impacts of crop water deficit (CWDI) on winter wheat growth periods in the main wheat planting belt of China. The results showed that wheat often had unbalanced water budgets, leading to serious and frequent CWDI in North China Plain (NCP) and Northwestern China (NW), especially during the pre-anthesis periods from greening to jointing and jointing to anthesis. Water deficit during these two phenological periods caused considerable yield reductions of 60% and 55%, respectively, compared to conditions of sufficient water supply. In contrast, in Xinjiang (XJ), extreme and frequent water deficit had a significant negative impact on yield during both pre- and post-anthesis periods. The contribution of different irrigation scenarios to wheat growth and yield was analyzed using the CERES-Wheat model in the Decision Support System for Agrotechnology Transfer (DSSAT). Results indicated that the critical irrigation scenario (CI) was pivotal to alleviating water deficit effects during key growth periods, enhancing wheat growth, and leading to a 51%−92% yield increase compared to rain-fed yields in NCP and NW. Moreover, CI could result in both high WP and high-yield water productivity (HYP) at most CWDI levels (except for extreme). Adding additional irrigation at heading to ensure post-anthesis water requirements were met can simultaneously increase WP and HYP while maintaining higher yields in the extreme water scarcity region XJ. These results imply that winter wheat responses to water deficit vary by growth periods and regions, making optimized irrigation strategies an effective practice to mitigate water shortage and ensure food safety.