Variation in Cd accumulation among radish cultivars and identification of low-Cd cultivars

Heavy metals have serious health consequences and ecosystem impacts. A pot experiment was conducted to investigate the variation of cadmium (Cd) uptake and accumulation among 40 cultivars of radish (Raphanus sativus L.) at three Cd levels, including 0.31 (T1), 0.83 (T2), and 1.13 (T3) mg kg^-1. Most of the tested cultivars had higher taproot biomass in the T3 treatment when compared to those in the T1 treatment, indicating a Cd stress-induced growth in radish. Taproot Cd concentrations in 95 and 5% of the tested cultivars were lower than 0.1 mg kg^-1 (fresh weight, FW) in the T1 and T2 treatments, respectively; however, there was no cultivar suitable for safe consumption in the T3 treatment. Radish production showed potential risk of Cd pollution as high as some leafy vegetables when grown in the soils where Cd concentration exceeded 0.8 mg kg^-1. When compared with Chinese heat-resisting or imported cultivars, Chinese common cultivars had significantly higher taproot Cd concentrations. Three low-Cd cultivars and five high-Cd cultivars were identified. Taproot Cd concentrations showed significant correlations between any two of the three treatments (p < 0.01), suggesting that Cd accumulation in taproot of radish was genotype-dependent.