Cadmium uptake by cowpea and mungbean as affected by Cd and P application

A green house experiment was conducted to determine the interactive effects of cadmium (0, 2.5, 5, 10, and 20 mg Cd kg(-1) soil) and phosphorus (0, 20 and 40 mg P kg(-1) soil) on dry matter yield of cowpea and mungbean, and t issue concentration and uptake of cadmium (Cd) and Phosphorus (P). Applicat ion of Cd to soil decreased the dry matter yield of both the crops signific antly at each level of applied P. Phosphorus application, on the other hand , increased the dry matter yield of both crops significantly at each level of Cd additions to the soil. Cadmium concentration in plant tissue and upta ke of Cd by plants increased markedly with the increasing rates of Cd in th e soil. The magnitude of increase in tissue Cd concentration, however, was higher in the absence than in the presence of added P. Consequently, the co ncentration of Cd in plants decreased with increasing levels of P applicati on to the soil. This decrease in tissue Cd concentration with increasing P supply in the soil was mainly attributed to increased dry matter yield of c rops. The concentration of P in cowpea and mungbean tissue increased while the uptake of P by these crops decreased markedly with increasing levels of Cd in the soil, irrespective of the rates of P applied.