近几年,我们发现一些果园采用在幼树树干基部培大土堆的防寒方法。八九年春季我们通过调查发现,凡是冬季进行幼树树干基部培土堆的果园,培上以上枝条几乎全部死亡。幼树培土防寒之所以造成严重抽条,主要是早春3月气温回升较快,枝条开始活动失水,而地下根系由于培土加厚了冻土层,根系土壤解冻晚,根系部位的土壤升温慢,造成地上地下严重失调所致。幼树正确的防寒方法主要有以下几点: (1)新栽幼树一般埋土防寒,即把苗木向北弯倒埋入土中,埋好拍实后的覆土厚度以30-40cm为宜。来年果树发芽时(不宜太早)再扒出幼树扶直。这种防寒法,即可保温减少蒸腾,又可防止抽条。 (2)对植株稍大不易弯倒的树,冬季可在树干的北侧40-50cm处,修筑高60cm,长1.2m的半月牙形土埂,使土埂南面有一个背风向阳的小环 In recent years, we have found that some orchards use the cold-proofing method of mounding the mound at the base of saplings. In the spring of 1989, we found through surveys that in the orchard where the saplings of the young tree trunk were mined in the winter, almost all of the above branches were dying. The reason why young trees prevent soil from freezing is the result of serious pumping. The temperature rises sharply in early spring in March, and the branches begin to lose water activity. However, the underground roots are thickened by frozen soil, the root soil is thawed later, , Resulting in a serious imbalance in the ground caused by. Young trees correct cold methods are the following: (1) The new planted saplings are generally buried cold, that is, the seedlings bent north bend buried in the soil, buried to shoot after the actual thickness of the soil to 30-40cm appropriate. Next year when fruit trees sprout (should not be too early) and then pick out young trees upright. This cold method, which can reduce heat transpiration, but also to prevent the strip. (2) Trees slightly harder to fall to the plant, in winter 40-50cm north of the trunk, the construction of 60cm high, 1.2m long crescent-shaped soil 埂, so that there is a southern levee lee sunny ring