帮我翻译：本研究根据1981-2020年我国冬小麦主产区内134个气象站点的逐日气象数据及129个农业试验站点的观测资料分析了作物水分亏缺指数CWDI、相对湿润度指数MI、需水量ETm及缺水量ETwd的时空演变特征并选取79个具有完整产量数据的典型农业试验站点量化了干旱胁迫对冬小麦产量的影响。研究结果表明在空间分布上中国冬小麦干旱胁迫变化呈现明显的生态区域差异其中北部冬麦区干旱胁迫最为严重不同生育

This study analyzed the spatiotemporal characteristics of crop water deficit index (CWDI), relative humidity index (MI), water demand (ETm), and water deficit (ETwd) for winter wheat in the main production areas of China from 1981 to 2020 using daily meteorological data from 134 meteorological stations and observational data from 129 agricultural experiment stations. A total of 79 typical agricultural experiment stations with complete yield data were selected to quantify the impact of drought stress on winter wheat yield. The results showed that there were significant ecological regional differences in the changes of drought stress in China's winter wheat production areas, with the most severe drought stress occurring in the northern winter wheat region. The frequency of drought during different growth periods reached the highest value in the northern winter wheat region, and about 21% of the entire winter wheat production area experienced severe drought. Water demand and water deficit showed a "north high and south low" distribution pattern in space, which was consistent with the pattern of drought stress change. Over time, the drought stress gradually increased in different sub-regions with the advancement of growth stages, and the water demand and water deficit also showed a significant upward trend. The most severe changes in drought stress, water demand, and water deficit occurred in the middle and lower reaches of the Yangtze River winter wheat region. The interannual variation of drought stress was significantly related to the interannual fluctuation of winter wheat yield, and the yield losses caused by drought stress were mainly concentrated in the northern winter wheat region, with an average annual reduction rate of 0.03%. These research results provide technical support for the quantitative prediction and warning of the impact of drought stress on China's wheat production, as well as the formulation of adaptive strategies.