抗寒剂和高油菜素内酯对高原水稻抗冷性的影响

THE EFFECT OF COLD RESISTANT AND HOMOBRASSINOLIDE ON THE CHILLING RESISTANCE OF PLATEAU RICE

抗寒剂ＣＲ－４，高油菜素内酯ＢＲ－１２０分别浸种和喷洒在水稻二叶期叶面上，经低温（２±１℃）暗胁迫２ｄ，根干重、根长和茎叶干重，叶片的超氧物歧化酶（ＳＯＤ），过氧化物酶（ＰＯＸ）活性和还原性谷胱甘肽（ＧＳＨ）含量皆高于对照。抗性强的丽粳低温胁迫时清除活性氧的效果较好。回温恢复（２５±１℃，３０００ｌｘ、１２ｈ／ｄ）１～５ｄ、抗性不同的两个品种的ＳＯＤ和ＰＯＸ活性、ＧＳＨ和抗坏血酸（ＡＳＡ）含量继续增加，丙二醛（ＭＤＡ）含量都有下降。但抗性弱的秀子糯回温恢复时，清除活性氧的效果较好，ＰＯＸ活性和ＧＳＨ含量增加较为显著。ＣＲ－４或ＢＲ－１２０处理在一定程度上提高了水稻幼苗活性氧清除系统的能力，增强了抗冷性。

The cold resistant CR-4 and homobrassinolide BR-120 were used by soaking seeds of rice and then spraying on the leaves at the diplophyllous stage,respectively.After chilling stress (2±1℃) in dark for two days,the root system of the rice seedlings was more flourishing,the dry weight of root was heavier and the root length was longer than the untreated control sample.The dry weight of stem plus leaf increased and the activities of superoxide dismutase (SOD) and peroxidase (POX),and the content of glutathine (GHS) increased notably.At chilling stress,the effect of scavenging activated oxygen in the variety with strong cold resistance was better.When the test samples regained room temperature for 1～5 days (25±1℃,3000 1x,12 h/d),the activities of SOD and POX,and the content of GSH and ascorbic acid (ASA) in leaves of two varieties showing strong or weak cold resistance increased continuously.The content of molondialdehyde (MDA) (a product of lipid peroxidation of membrane) decreased.But in the period of regaining temperature,the effect of scavenging activated oxygen in the variety with weak cold resistance was better and the increases of activity of POX and content of GSH were more obvious.It is suggested that treatments of CR-4 and BR-120 increase the ability of scavenging activated oxygen in rice seedlings and strengthen the cold resistance of the varieties to some extent.