西峰黄土高原冬季积温变化对作物发育期的影响

用黄土高原西峰站1965-2005年冬季积温和1981—2005年冬小麦、苹果、梨树发育期资料，分析了冬季积温和作物发育期的变化规律，用相关计算和典型年份对比方法探讨了冬季积温对作物发育期的影响。结果表明：1965—2005年冬季积温增加率为5．5℃·d／a，2000年以来持续为正距平，1994年以后作物发育期持续变早；冬季积温与冬小麦各发育期呈明显的负相关，最显著的是返青期，其次是抽穗期，再次是起身期；冬季积温典型偏高年份（1986、1998、2000年）均比典型偏低年（1983、1984、1988年）的发育期提前，冬小麦最明显的是全发育期提前了21d，苹果最明显的是叶变始期提前了19d，梨树最明显的是叶变盛期提前了20d。研究结果对掌握作物发育期的变化规律以及物候预测有一定意义。

Influence of Changes of Accumulation Temperature in Winter on Crop Growing Periods in Loess Plateau of Xifeng

Based on the data of the accumulation temperature in winter from 1965 to 2005 and the data of the growing period of winter wheat, apple and pear trees from 1981 to 2005 in Xifeng station, changes of the accumulated temperature in winter and crop growing periods were analyzed, by using correlation and comparison to typical years. The results indicated that the accumulated temperature in winter increased 5.5℃ per year from 1965 to 2005. The Crops＇ growing period had advanced since 1994. The accumulated temperature in winter was negatively related to the growing period of winter wheat, significantly for returning green, heading and jointing stage in turn. In typical years with higher winter accumulation temperature, such as 1986, 1998 and 2000, the crop growing period advanced more than in the typical years with lower winter accumulation temperature such as 1983, 1984 and 1988. The total length of growing period of winter wheat advanced 21 days, and for apple tree the leaf color change stage advanced 19 days, while the middle stage of the leaf color change of pear tree advanced 20 days.