Differential accumulation and distribution of cadmium and lead in two water spinach cultivars and their hybrid grown in contaminated soils

A pot experiment was carried out to study the differences of absorption and translocation of Cd and Pb in two water spinach (Ipomoea aquatica Forsk.) cultivars and their hybrid differing in shoot Cd and Pb concentrations and the influence of hybridization on the uptake and accumulation of Cd and Pb. A typical low-Cd-Pb cultivar, cv. QLQ, a typical high-Cd-Pb cultivar, cv. T308, and a hybrid from the former two cultivars, QLQ×T308, were grown in five soils with different concentrations of Cd and Pb. The results showed that cv. QLQ with the lowest shoot Cd and Pb concentrations had the highest root Cd concentration and the lowest root Pb concentration in comparison with cv. T308 and the hybrid. Total accumulation of Cd and Pb in cv. QLQ was significantly lower (p 0.05) between cv. T308 and the hybrid. Cd uptake by cv. QLQ was mainly restrained in root but that by cv. T308 was primarily transported to shoot. In addition, shoot Cd and Pb concentrations were positively and significantly correlated (p 0.05) between shoot Pb concentration and translocation rate of Pb. These results indicated that the difference of shoot Cd concentration among the cultivars was attributable to the differences of Cd uptake and translocation from root to shoot but the difference of shoot Pb concentration appeared to be driven by whole-plant Pb uptake rather than by Pb translocation. Crossbreeding is not a practical method to minimize Cd and Pb accumulation in water spinach.