6～8年生以下的苹果幼树越冬死亡现象中,最主要的原因不是日灼和低温(组织变色),而是枝条脱水干枯,即所谓“抽干”。抽干的生理原因,是由于枝条内部大量水分,长期处于濒繁而遽烈的结冻、解冻相交替的状态下,从而造成严重的蒸腾失水;尤其是2～3月里解冻天气的高温,和进一步的大气干旱(包括旱风),更加深了细胞 6 to 8 years old apple tree overwintering death phenomenon, the main reason is not the sunburn and low temperature (tissue discoloration), but the branches dry dehydration, the so-called “pumping dry.” The reason of pumping dryness is due to the large amount of water inside the branches, long-term in the brink of intense and intense freezing, thawing phase alternating state, resulting in severe transpiration dehydration; especially from February to March thaw weather high temperature , And further atmospheric drought (including dry wind), deepened the cells