冻害是指果树在生长期夜晚土壤和植株表面温度短时间降至0℃或以下,致使果树幼嫩部分遭受伤害的现象。我国平均每年霜冻危害面积达34万hm~2,最重的年份达77万hm~2,每年造成农作物,果树和蔬菜损失达30亿元。特别是近年来,我国北方晚霜冻害尤为严重,一些春季开花早的果树,经常遇到晚霜危害,轻者减产,重者 Frost damage refers to the fruit trees in the growing season night soil and plant surface temperature dropped to 0 ℃ or less, resulting in the young part of the tree was hurt phenomenon. The annual frost damage area in China is 340,000 hm ~ 2 and the heaviest year reaches 770,000 hm ~ 2, causing an annual loss of 3 billion yuan for crops, fruit trees and vegetables. Especially in recent years, the frost damage in the northern part of China is particularly serious. Some fruit trees with early flowering in spring often encounter night-frost damage, with the light output and heavy output reduced