Mitigating cadmium (Cd) toxicity and enhancing growth, yield, and antioxidant defence of wheat (Triticum aestivum L.) through silicon fertilizers

Cadmium (Cd) stress in agricultural soils poses a significant threat to wheat production, food safety, and human health. Wheat productivity is severely hampered by Cd toxicity; however, to overcome this problem silicon (Si) fertilization has emerged as a promising strategy to mitigate heavy metal toxicity in plants; in this study, we compare the efficacy of natural and synthetic Si fertilization sources in modulating wheat growth, Cd accumulation, and antioxidant responses under Cd-contaminated soil. The Si was used as Ca silicate at 75 kg ha-1 (synthetic Si source), and the rice husk at 150 kg ha-1 (natural Si source) with and without humic acid (10 mg kg-1 of soil) in comparison to control (Cd stress). Both Si sources were found to significantly boost the growth and yield attributes of wheat, while Cd stress significantly increased the electrolyte leakage that triggered oxidative stress. However, both Si sources decrease the oxidative stress and increase the superoxide dismutase and peroxidase activities. Si fertilization also inhibited the uptake of Cd from roots and its translocation to shoots and grains of wheat plant. In comparison, the synthetic Si fertilization was more effective than natural Si fertilization as it produced highest increase in plant height (21.40%), grain yield (25.21%), and reduced Cd concentration in root (42.60%) and shoot (59.71%) than control (Cd stress). Conclusively, Si fertilization (preferably Ca silicate at 75 kg ha-1) alleviates the opposing impact of Cd on wheat growth by strengthening the antioxidant defense system, decreasing the Cd uptake and its translocation to humans.