Effects of Cd-Pb interaction on the accumulation of Cd and Pb in four water spinach cultivars

A pot experiment was conducted to investigate the effects of interaction between Cd and Pb on shoot Cd and Pb accumulation in four water spinach (Ipomoea aquatica Forsk.) cultivars, including two low-Cd-Pb cultivars and two high-Cd-Pb cultivars, the stability of low-Pb trait in low-Cd-Pb cultivars, and the variation of transportation of Cd and Pb from soil to shoot under Cd-Pb joint exposures. The four cultivars were grown in five soils with different concentrations of Cd and Pb. The results showed that shoot Cd and Pb concentrations of low-Cd-Pb cultivars were always significantly lower than those of high-Cd-Pb cultivars and the increase of soil Pb promoted Cd accumulation and enhanced Cd bioconcentration factor (BCF) values in all water spinach cultivars. However, the increase of soil Cd inhibited Pb accumulation in the shoots of all the cultivars and decreased the Pb BCF values in Cd-Pb contaminated soils. Lead has an enhancing effect on increasing the shoot Cd accumulation and cadmium has an inhibitory effect on the uptake of Pb by the shoot of water spinach when grown in combined contaminated soils by Cd and Pb.