本文利用1955-2013年庆阳市西峰气象站气象数据及1991-2013年西峰区冬小麦、春玉米和马铃薯产量统计数据,分析了该区域气象干旱特征及其对作物产量的影响.结果表明:(1)近60年来,董志塬区的降水量和干燥度年际变化显著,1985年之后起伏进一步加大.整体上看,降水量呈微弱下降趋势,干燥度表现出微弱上升趋势;多年平均降水量为550.6 mm,多年平均干燥度为1.81.干燥度最大值出现在1995年,为3.22,相应年份的降水量负距平达到了最大值(-216.9 mm).(2)前一年8-9月份降水量及干燥度对当年冬小麦产量的影响都达到了极显著水平(P<0.01),表明播种前底墒对冬小麦产量影响很大;6-7月份干燥度、降水量对春玉米产量的影响达到了显著水平(P<0.05),其中,7月份的影响最大;而在6月份,干燥度对马铃薯产量的影响达到显著水平,但降水量对其产量的影响却未达到显著水平.粮食产量除了受到气象条件的影响外,品种、管理措施也是影响其变化的重要方面.%Based on the daily meteorological data of Xifeng weather station during the period of 1955-2013 and the yield data of winter wheat ,spring maize and potato from 1991 to 2013 in Dongzhi Loess Plateau ,the characteristics of meteorological drought and its impacts on crop yield in this area were analyzed .The results showed following :(1 ) The inter-annual variations of precipitation and aridity index in the Dongzhi Loess Plateau fluctuated significantly in the last 60 years ,and the fluctuations increased after 1985 .Generally ,the precipitation anomaly decreased slightly ,but the aridity index (AI ) showed a slightly increasing trend .The mean value of precipitation and aridity index were 550 .6 mm and 1 .81 ,respectively .In 1995 ,both negative precipitation anomaly and aridity index had the maximum values ,which were-216 .9 mm and 3 .22 respectively .(2) The aridity index from August to September in the previous year had a signifi-cant effect on winter wheat yield ,which demonstrated that the soil water storage before sowing had great influence on win-ter wheat yield .The yield of spring maize was affected remarkably ( P<0 .05 ) by the AI and precipitation in June and July ,especially in July .Potato yield was significantly affected by the AI rather than precipitation in June .Furthermore , the crop yield was influenced not only by meteorological conditions ,but also by crop varieties and management measures .
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