Accumulation of cadmium in the edible parts of six vegetable species grown in Cd-contaminated soils

Species difference in Cd accumulation is important for selection of agronomic technologies aimed at producing low-Cd vegetables. Six vegetable species (Chinese leek, pakchoi, carrot, radish, tomato and cucumber) were grown in pot and field experiments to study the accumulation of Cd under different conditions. In the field trial (Cd 2.55 mg kg−1), Cd concentrations in the edible parts ranged from 0.01 to 0.1 mg kg−1 and were below the permissible limits (0.2 mg kg−1 for pakchoi and leek; 0.1 mg kg−1 for carrot and radish; 0.05 mg kg−1 for cucumber and tomato), but exceeded the limit in pakchoi, Chinese leek, carrot and tomato at a Cd addition level of 2.0 mg kg−1. Plant Cd concentrations increased linearly with the increasing concentration of Cd added to the soil, with the slope of the regression lines varying by 28-fold among the six species. The bioconcentration factor (BCF) varied substantially, and was much higher in the pot experiment than in the field trial. It is concluded that the vegetable species differed markedly in the Cd accumulation and species performed consistently under different growth conditions.