Variation Characteristics of Main Meteorological Restricting Factors for Apple Production in Northern Yanan
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Abstract:
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 over10℃ accumulated temperature is over 3200 ℃, being a relative warm period, in which the temperature meets the needs of apple growth and development; besides the midApril, 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.