在三四月份,小麦已先后完成了春化阶段和光照阶段的发育,此时抗寒能力降低,丧失了抗御0℃以下低温的能力,此时若寒潮来临,夜间晴朗无风,地表层温度骤降到0℃以下,便会发生早春冻害。发生春霜冻害的小麦,叶片似被开水浸泡过,经过太阳照晒便逐渐干枯。包在叶内的茎顶端幼穗分生细胞对低温反应比叶细胞更敏感。幼穗在不同的发育时期受冻程度有所不同,一般来说,已进入雌雄蕊原基分化期(拔节初期)的易受冻,表 In March and April, wheat has completed the vernalization and photoperiod development stages, at which point the ability to resist cold is reduced and the ability to resist low temperatures below 0 ° C is lost. At this time, if the cold comes, the clear and windless at night, the surface temperature Suddenly dropped below 0 ℃, will occur in early spring frost damage. Spring frost damage occurred in wheat leaves seem to be soaked in water, after the sun will be gradually drying the sun. The shoot apical meristem cells encased in leaves are more sensitive to hypothermia than leaf cells. Young panicles have different degrees of freezing at different developmental stages. In general, the panicle has entered the pistil and stamen primordial differentiation period