延安北部苹果生产主要气象限制因子变化特征

利用当地气象观测资料，分析延安北部4县苹果生产主要气象限制因子的变化特征和对发展苹果种植业的影响。结果表明：1986年以来，延安北部4县气温呈现上升趋势，特别是1997年以后，气温上升明显。1997-2005年，吴起、志丹年平均气温在8℃以上，大于等于10℃积温达到3200℃以上，进入相对温暖期，温度可满足苹果生长发育需求。除4月中旬外，春季各旬的最低气温升高，花期冻害温度出现次数减少一半。冻害出现的时段可能将主要集中在花蕾期。年降水量在60年代明显偏多，吴起、志丹年降水量超过500mm。1968年后降水缓慢减少，90年代降水最少，2001年后，降水量增多，但仍未达到苹果生长所需的适宜值。

Variation Characteristics of Main Meteorological Restricting Factors for Apple Production in Northern Yanan

The variation characteristics of the main meteorological restricting factors for and the influences on apple production in the 4 northern counties of Yan＇an are analyzed by means of the local meteorological observation data. The results indicate that there was an increasing tendency in temperature in the 4 northern counties of Yan＇ an since 1986, especially after 1997. From 1997 to 2005, the annual average temperature was 8 ℃ higher in Wuqi, Zhidan, and the over-10℃ accumulated temperature is over 3200 ℃, being a relative warm period, in which the temperature meets the needs of apple growth and development; besides the mid-April, the minimum temperature of each dekad in spring rose; the number of freezing injury occurrence in the flowering period reduced by half, and the freezing damage occurred mainly in the bud stage; there was much more precipitation in the 1960s＇, with the mean annual precipitation of Wuqi and Zhidan being over 500 mm; the rainfall decreased slowly after 1968 with the minimum in the 1990s＇ ; after 2001, the precipitation increased, but still cannot reach the suitable level for the growth of apple.