【摘要】 苹果花芽遭受冻害时,通过甲基绿—派洛红的染色反应显示细胞核从嗜甲基绿性变为嗜派洛红性,反应DNA从高聚合状态降解到低聚合状态。以核的嗜派洛红性为标志,显示苹果花芽冻害最先发生在花芽基部的维管束,继而是髓细胞,花芽上部的花器官原基分生细胞相对比较抗寒。花芽在寒冬时期(12月中下旬～2月下旬)开始遭到冻害,到早春(3、4月)死亡。抗寒性较弱的‘金冠’花芽在日低温-17℃±开始遭到冻害;抗寒性中等的‘金红’花芽在日低温-20℃±开始受冻;抗寒性强的‘黄太平’在整个越冬过程中绝大部分花芽始终保持正常染色反应,不产生核的嗜派洛红性。更多还原

【Abstract】 The present experiment showed that, when the apple flower buds were subjected to freezing injury, the green colour of nuclei stained with methyl green was transfered to the red one by pyronin , indicating the degradation of DNA from high polymerization into low polymers ( depo-lymerized DNA ) . Using the red feature of nuclei stained by pyronin as an indicotor, it was exhibited that the primary site of freezing injury was in the vascular bundles of the basal part of flower buds , and then in the pith cells, while the meristematic cells in the upper part of flower buds were relatively cold resistant. The apple flower buds met with pri-mary freezing injury during hard winter period, and died in early spring ( from March to April ) . The flower buds of Golden Delicious , which was less cold resistant, began to be subjected to freezing damage at the low temperature of - 17℃ daily, and Golden-Red one with mediate cold hardiness was at -20℃. The normal reaction stained with methyl green-pyronin is always maintained in most of flower buds of strong hardy Huangtaiping variety in the overwintering period.更多还原