白茅生长及抗氧化酶系统对铜胁迫的生理响应

通过盆栽实验研究了重金属Cu递进胁迫对白茅幼苗生理生态及抗氧化酶系统的影响。结果表明,随着Cu浓度的增加,平均根长、平均株高、鲜重、干重以及叶片色素含量等指标先增后降,分别在Cu浓度500 mg/kg处达到峰值。最长根长和叶片可溶性蛋白含量则在1000 mg/kg处达到峰值。说明低浓度Cu（〈500 mg/kg）对白茅生长有促进作用,而高浓度Cu（〉1000 mg/kg）则对植株生长产生抑制作用。Cu胁迫还导致叶片细胞膜脂过氧化水平增高,表现为叶片MDA含量随Cu浓度增加而持续上升,其最大值达到对照的5.3倍。抗氧化酶系统中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和多酚氧化酶（PPO）活性也随Cu浓度增加表现出先升后降的趋势,并均在Cu浓度为1000 mg/kg时达到峰值,但过氧化物酶（POD）活性持续上升,故系统受到高浓度Cu胁迫而失衡,不能有效清除植物体的自由基和过氧化物,使植物产生受害症状。

Physiological response of Imperata cylindrica var.mayo seedlings on growth and antioxidant enzyme system under Cu stress

The effects of copper（Cu） progressive stress on the seedlings growth and antioxidant enzyme system of Imperata cylindrica var.majo were studied by pot experiments.The result showed that with enhancing of Cu treatments concentrations,the average length of root,average height,fresh/dry weight,and the chlorophylls contents of seedlings decreased constantly after increased slightly at first,reached their peaks at Cu concentration of 500 mg/kg,expect of that the maximum length of root and soluble protein content reaching the peaks at Cu concentration of 1000 mg/kg.It showed that growth of I.cylindrica var.majo seedlings was improved at low concentration of Cu（ 500 mg/kg）,while inhibited at high Cu concentration（ 1000 mg/kg）.The level of peroxidation of cellular membrane lipids and MDA contents of seedlings increased continuously under Cu stress,and the maximum value was 5.3 times higher than the control.Furthermore,with increasing of Cu concentration,it increased slightly at first and reached its peaks at Cu concentration of 1000 mg/kg.Meanwhile,the peroxidase superoxide dismutase（SOD）,catalase（CAT） and polyphenol oxidase（PPO） activities all decreased constantly after（POD） activity increased continuously.It indicated that the balance of protective enzyme system was broken under high Cu stress,and radicals and peroxides could not be scrubbed effectively,which caused the hurt symptom in the seedlings.