effect of copper and zinc on the uptake of cadmium by corn and sunflower

abstract heavy metals enter to human food chain through the plant and soil contamination. it is very important to evaluate the affecting factors on plant uptake of heavy metals. in this study the effects of copper and zinc availability on cadmium uptake of root and shoot of corn and sunflower was investigated. the experiment was carried out with a factorial arrangement, two species of plants (sunflower and corn), two cadmium concentrations (0.02 and 0.05 mg /l) and three concentrations of zinc and copper ( 0, 0.025 and 0.05 mg/l for zinc and 0, 0.01 and 0.02 mg/l for copper) based on a completely randomized design with three replications. the results showed that copper and zinc availability had no effect on cadmium uptake of corn plant. the highest concentration of cadmium in root corn was observed in 0.05 mg/l of cadmium concentration without copper application. in sunflower, the addition of 0.05 mg/l zinc to medium decreased cadmium uptake in 0.02 and 0.05 mg/l cadmium treatments. the synergistic effect of cadmium and zinc was observed in 0.05 mg/l cadmium and 0.025 mg/l zinc treatments. zinc concentration had a positive effect on cadmium uptake in root and shoot of sunflower in this treatment.