The increased frequency of severe drought events has increased the global water supply security risks, posing a substantial threat to food crop yields such as rice. Therefore, it is crucial to accurately regulate rice irrigation thresholds and optimize the coordination between rice irrigation and the water demand of other industries under severe drought conditions. This study employed the WOFOST model to simulate rice yield in Chuxiong Yi Autonomous Prefecture, Yunnan Province, under various irrigation scenarios, focusing on severe drought conditions. Optimal irrigation schemes and corresponding irrigation thresholds were determined for different yield reduction rates during 90 % and 95 % extremely dry years, utilizing predefined rates of irrigation contribution, yield reduction, and water productivity. The results are as follows. (1) During extremely dry years, irrigation during the jointing-booting, heading-flowering stages can boost the yield by up to 218 % and 270 % compared to the yield without irrigation, respectively. Based on irrigation water productivity, it can be advisable to avoid reducing irrigation during the jointing-booting stage and heading-flowering stage. (2) The irrigation threshold varied according to the severity of drought. (3) During three consecutive years of severe drought, rice yield exhibited an annual decreasing trend, aiming to minimize comprehensive economic losses and optimize water utilization efficiently. This study can provide decision support for the hierarchical regulation of crop irrigation thresholds under severe drought conditions.

中文翻译：

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严重干旱条件下作物灌溉阈值的层次调控研究


严重干旱事件的频率增加增加了全球供水安全风险，对水稻等粮食作物产量构成重大威胁。因此，在严重干旱条件下，准确调控水稻灌溉阈值，优化水稻灌溉与其他行业用水需求的协调至关重要。本研究采用 WOFOST 模型模拟云南省楚雄彝族自治州在各种灌溉情景下的水稻产量，重点关注严重干旱条件。利用预定义的灌溉贡献率、减产率和水生产力率，确定了 90 % 和 95 % 极端干旱年份不同减产率的最佳灌溉方案和相应的灌溉阈值。结果如下。（1） 在极度干旱的年份，与不灌溉的产量相比，在拔节-结穗、抽穗-开花阶段进行灌溉可分别提高 218% 和 270 % 的产量。根据灌溉水生产力，建议避免在拔节-孕穗阶段和抽穗-开花阶段减少灌溉。（2） 灌溉阈值根据干旱的严重程度而变化。（3）在连续三年严重干旱期间，水稻产量呈逐年下降趋势，旨在最大限度地减少综合经济损失并有效优化水资源利用。本研究可为严重干旱条件下作物灌溉阈值的分级调控提供决策支持。