帮我润色但不改变原意：最后根据模型Ⅲ中冬小麦单产对干旱胁迫的敏感系数结合各亚区干旱胁迫的年变化趋势分析得到干旱胁迫条件下单产年变化率的空间分布图和各亚区箱式分布图图2-12。结果表明在整个冬小麦生长季部分亚区受干旱胁迫年变化趋势的影响冬小麦单产表现出显著下降的趋势。80年代冬小麦单产在西南冬麦区大部以005年-017年的平均速率显著下降。90年代相比80年代减产率高值区逐渐由西南冬麦区向北部冬麦区

According to the sensitivity coefficients of winter wheat yield to drought stress in Model III and the annual variation trends of drought stress in various sub-regions, the spatial distribution map of yield annual variation rates and box plot distribution charts of each sub-region under drought stress conditions were analyzed and obtained (Figure 2-12). The results showed that during the entire winter wheat growing season, some sub-regions were significantly affected by the annual variation trends of drought stress, and winter wheat yield showed a significant downward trend. In the 1980s, winter wheat yield significantly declined at an average rate of 0.05%/year-0.17%/year in most of the Southwest Winter Wheat Region. Compared with the 1980s, in the 1990s, the high-value area of yield reduction gradually shifted from the Southwest Winter Wheat Region to the North Winter Wheat Region and the Yangtze River Middle and Lower Reaches Winter Wheat Region. The highest reduction rate could reach 0.36%/year. Under drought stress, the spatial distribution characteristics of yield annual variation rates in the 2000s were similar to those in the 1990s. In the 2000s, 81.3% of winter wheat sites in the main production areas showed a decrease in yield. In the 2010s, the high-value area of yield reduction was mainly concentrated in the eastern part of the North Winter Wheat Region, with a significant decrease rate of -0.01%year-0.22%/year. Overall, as the years went by, the annual variation rate of winter wheat yield gradually decreased, with the North Winter Wheat Region showing the most significant downward trend.