Biochemical responses of Pisum Sativum L. under cadmium and mercury regimes

The effects of cadmium and mercury toxicity (30, 60,90 and 120 mu M) on seed germination, growth, pigments and total proteins of Pisum sativum (cv. Master Lee) were assessed. Seed germination was not affected by any of the metal tested, whereas initial growth was strongly inhibited by increasing concentrations of cadmium. Seedling biomass declined considerably in the presence of both metals. However, seedling growth was more influenced by varying levels of cadmium than mercury. Chlorophyll content showed a progressive decrease with increasing concentrations of cadmium and mercury. Protein content increased at 30 mu M of mercury and at 60 and 90 mu M of cadmium but decreased at the maximum level of both metals. Toxicity of both metals was expressed in terms of both morphological and biochemical variables. The accumulation of metals in root and shoot was concentration dependent. However, more cadmium deposited in shoots than in roots while the reverse was true for mercury. From these results, it was concluded that P. sativum had shown some tolerance towards various cadmium and mercury levels. It is likely that certain repair mechanisms can be attributed to metal tolerance in this species. Thus the species could be a useful phytoremediator for cadmium and mercury contamination.