Effect of lead stress on membrane and antioxidant systems in Vetiveria zizanioides leaves

Effects of lead stress on the membrane and antioxidant systems in Vetiveria zizanioides leaves were studied.The results showed that the chlorophyll(Chl) content and SOD,POD and CAT activities increased,as compared to the control,when lead concentration was less than 500 mg L-1.These stress indices decreased when lead concentration was greater than 500 mg L-1.Meanwhile,the chlorophyll a/chlorophyll b ratio remained relatively constant.With increasing lead stress,the relative membrane permeability and MDA content increased considerably.A positive correlation between them was observed.The AsA content varied significantly,while GSH remained practically unchanged.And,the biomass of V.zizanioides decreased significantly at lead concentration of 1000 mgL-1 and 2000 mgL-1.