水稻幼苗冷锻炼过程中钙的效应

冷锻炼处理提高了水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）幼苗叶片中抗氧化剂（还原型谷胱甘肽，ＧＳＨ；抗坏血酸，ＡｓＡ）含量和膜保护酶（超氧化物歧化酶，ＳＯＤ）的活性，同时也提高了可溶性蛋白质中热稳定蛋白的含量。ＣａＣｌ２ 浸种处理对上述冷锻炼的作用有加强的效果，且明显地提高了过氧化氢酶（ＣＡＴ）和过氧化物酶（ＰＯＤ）的活性。有无ＣａＣｌ２ 处理的冷锻炼处理均减轻冷胁迫引起的ＧＳＨ 及ＡｓＡ 含量、ＳＯＤ 活性及热稳定蛋白质含量的下降程度，有利于幼苗在恢复过程中ＧＳＨ、ＡｓＡ、ＣＡＴ、ＳＯＤ、ＰＯＤ及热稳定蛋白质水平迅速回升。结合ＣａＣｌ２ 处理的冷锻炼苗在冷胁迫恢复生长时增长迅速，且苗健壮浓绿，说明ＣａＣｌ２浸种对冷锻炼处理提高水稻幼苗的抗冷力有明显的促进作用，这与ＣａＣｌ２ 浸种结合冷锻炼能更有效的提高细胞膜保护能力有关

CALCIUM EFFECT ON THE PROCESS OF COLD HARDENING OF RICE SEEDLINGS

Rice seedlings for cold hardening were germinated from seeds treated with or without immersion in 30 mmol/L of CaCl 2 solution. Change of membrane system protectivity in leaves at various periods (viz: following cold hardening, chilling stress and on the 3rd day of recovery); the ratio of seedling survival and the ability of recovery were investigated. The results showed that cold hardening increased the contents of endogenous antioxidants (the reduced form of glutathione, GSH; ascorbic acid, AsA), SOD activity and the content of heat stable protein in soluble protein. Cold hardening combined with the CaCl 2 treatment of seeds enhanced the above mentioned effects of cold hardening, and obviously increased the activities of catalase (CAT) and peroxidase (POD). Both cold hardening with or without the CaCl 2 treatment reduced the declining degree of GSH, AsA content,the SOD activity and the heat stable protein content caused by chilling stress, augmented the increase in the level of GSH, AsA, CAT, SOD, POD and heat stable protein in the recovery periods. The CaCl 2 pretreatment especially had more effect on the level of heat stable protein, augmenting the A protein to rise to the level in normal seedlings. Furthermore, cold hardened seedlings from seeds pretreated with CaCl 2 grew faster and better in the recovery period of chilling stress than those from seeds without CaCl 2 pretreatment. This promotive effect of CaCl 2 treatment on seeds prior to cold hardening of seedling could be associated with an augmentation of membrane protectivity induced by the combined treatment.