淮河流域冬小麦晚霜冻时空演变分析

Temporal and Spatial Evolution on Late Frost Damage of Winter Wheat in Huaihe River Basin

为掌握气候持续变暖背景下淮河流域晚霜冻害的变化规律,基于1960-2016年61个气象站点的逐日地面0cm最低气温数据,计算霜冻频次、强度和变异系数,构建霜冻害危险指数,分析了淮河流域冬小麦生长季晚霜冻时空变化。结果表明:(1)57年中晚霜冻出现在3月11日至4月15日,整体呈提前趋势,速率达到-2.49d·年-1(P<0.05),晚霜冻的提前结束使冬小麦灌浆停滞和籽粒发芽力丧失的风险降低。(2)在冬小麦生长季延长的背景下,57年中轻度、中度、重度晚霜冻的频次都呈现减少趋势,变化倾向率分别为-9.14次·年-1(P<0.01)、-1.17次·年-1(P>0.05)、-5.81次·年-1(P<0.01)。年代变化上,重霜冻在灌浆至成熟阶段的频次在1980s上升趋势最显著,倾向率为6.73次·年-1(P<0.05)。1961-1990年中霜冻在拔节期的频次增加趋势最显著,倾向率为1.80次·年-1(P<0.05);1981-2010年重霜冻在拔节期的频次减少趋势最显著,倾向率为-3.46次·年-1(P<0.01)。(3)冬小麦晚霜冻在不同的生长阶段空间分异较大,呈不同分布模式。以开始拔节的日期为起点,高风险区和较高风险区在拔节后(1～5d)所占面积百分比最大,分别达到0.63%、80.68%。中风险区在抽穗至开花阶段(12～15d)面积百分比最大(81.68%),较低风险区在灌浆至成熟阶段(16～57d)占比最大(57.49%)。不同程度的晚霜冻频次在不同的时间段减少速率不同,在不同的生长阶段空间分布差异较大。

The occurrence of late frost damage in the key phonological period of winter wheat needs to be further analyzed in the context of continuous global warming.Based on daily minimum ground temperature from 61 meteorological stations in Huaihe River basin from 1960 to 2016,combining the phonological date of winter wheat and late frost date,we have calculated the frequency,intensity and coefficient of variation of late frost,and a frost hazard index was constructed.We obtained the temporal and spatial changes of late frost damage in the growing season of winter wheat.The results showed that the late frost date is between March 11th and April 15th in recent 57 years.As a whole,the late frost date showed an earlier trend,with the rate of-2.49 d·a^-1(P<0.05).Under the background of the extended growing season of winter wheat,in the past 57 years,the number of mild,moderate and severe late frost showed a decreasing trend,with the change tendency rate of-9.14 times·a^-1(P<0.01),-1.17 times·a^-1(P >0.05),and-5.81 times·a^-1(P<0.01),respectively.For inter decadal variation,the frequency of severe frost significantly increased in the period from grain filling to maturity with a propensity of 6.73 times·a^-1(P<0.05)in 1980s.Mild frost significantly increased at jointing stage,with the trend rate of 1.80 times·a^-1(P<0.05)between 1961 and 1990.Severe frost showed significant decreasing trend at jointing stage with a propensity of-3.46 times·a^-1(P<0.01)between 1981 and 2010.The late frost damage of winter wheat in different growing periods showed large spatial differences,with different distribution patterns.Starting from the jointing date,the high-risk area and the second-highest risk area took up the largest percentage of late frost damage after jointing stage(1-5 days),reaching to 0.63%and 80.68%,respectively.The mild risk zone from heading to flowering stage(12-15 days)accounted for 81.68%of the total area,and the lower risk area accounted for the largest proportion(57.49%)from grain filling to maturity stage(15-57 days).It can be concluded that different degrees of the frequency in late frost decreased at different rate,and spatial distribution varies greatly at different growth stages.