Effect of silicon on morpho-physiological attributes, yield and cadmium accumulation in two maize genotypes with contrasting root system size and health risk assessment

Background and aims: Cadmium (Cd) contamination is a serious threat to plants and humans. Silicon (Si) was reported to have some alleviative effects on Cd stress in plants. However, whether Si alleviates Cd toxicity in maize genotypes with contrasting root system size are unknown. Methods: Effects of Si application (200 mg kg⁻¹ soil) on shoot and root growth, Cd uptake and transportation under Cd stress (20 mg kg⁻¹ soil) were assessed at the silking and maturity stages of maize genotypes Zhongke11 (deep-rooted) and Shengrui999 (shallow-rooted) in a pot experiment. Results: Application of Si significantly increased root dry weight, plant height and root length. 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. Grain Cd concentration in the combined Cd and Si treatment was decreased by 14.4% (Zhongke11) and 21.4% (Shengrui999) than that in Cd 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 shallow-rooted genotype Shengrui999.