Abstract
Background and aims Cadmium (Cd) contamination is a serious threat to plants and humans. Silicon (Si) was reported to have some alleviative effects on plant tolerance to Cd stress. However, whether Si alleviates Cd toxicity in maize genotypes with contrasting root system size are unknown. Methods Effects of Si applications (0 and 200 mg kg-1 soil) on shoot and root growth, Cd uptake and transportation under Cd treatments (0 and 20 mg kg-1 soil) were assessed at the silking and maturity of maize genotypes Zhongke11 (large-rooted) and Shengrui999 (small-rooted) in a pot experiment. Results Root dry weight, plant height and root length were significantly affected by Si addition. Root volume and average root diameter were significantly positively correlated with root Cd concentration, bioaccumulation and translocation factor, respectively, of two maize genotypes at the silking stage. Addition of Si significantly increased Cd concentration, content, bioconcentration and translocation factor in roots of Zhongke11, but reduced the values of these parameters in Shengrui9999 at both growth stages. Under Cd stress, grain Cd concentration in the Si treatment was decreased by 14.4% (Zhongke11) and 21.4% (Shengrui999) than that in non-Si treatment. Grain yield was significantly negatively correlated with root Cd accumulation. Moreover, addition of Si significantly reduced Cd daily intake and health risk index in maize.Conclusions This study demonstrated that addition of Si reduced health risk by eliminating Cd accumulation in maize shoot and grain, and alleviated Cd stress with more profound effects in the small-rooted genotype Shengrui999.