小麦的冻害与低温的程度和时间的长短成正相关。一般年从12月中、下旬到次年2月上、中旬之间,当极端最低温度降至0℃以下时,是小麦发生冻害的首要条件之一。其次是小麦在分蘖、拔节阶段抗寒能力较强,拔节后进八孕穗和旗叶期,和抽穗后开花时的抗寒力下降,遇0℃以下低温会发生不同程度的冻害。进入孕穗以后,穗开始雌雄蕊分化,遇霜冻将引起叶、茎、穗受害,导致后期穗数减少,在旗叶期时花粉母细胞达四分体期,对低温很敏感,受冻后使花粉不 The frost damage of wheat is positively related to the degree of low temperature and the length of time. The general year from mid-December, late February to mid-February, when the extreme minimum temperature below 0 ℃, is one of the primary conditions for wheat frost damage. Secondly, the ability of cold-resistance of wheat at tillering and jointing stage was stronger, the booting and flag leaf stage at the eighth jointing stage and the cold resistance of flowering at heading stage were reduced, and frost damage would occur in the low temperature below 0 ℃. Into the booting, the ear began to stamen differentiation, the case of frost will cause leaves, stems, spike damage, resulting in reduced spikelets at the late flag stage pollen mother cells up to four quarters, very sensitive to low temperatures, after the freezing Pollen not