Foliar application of silicon and selenium reduce the toxicity of cadmium to soybeans

Silicon (Si) and selenium (Se), two environmental protection materials, which are beneficial to plant growth and stress resistance, can also alleviate crop stress induced by heavy metals. However, the effects of Si, Se and their interactions in reducing cadmium (Cd) toxicity and the related mechanisms require further elucidation. Hence, this study implemented a foliar application of Si and Se on soybean (Glycine max L.) that subjected to Cd-induced stress with four treatments (sole/combined application of Si, Se, no fertilizer treatment). The results demonstrated that Si and Se showed effective mitigation of Cd toxicity on soybeans mainly by promoting growth, enhancing photosynthesis, maintaining root vigor, improving antioxidant capacity, alleviating oxidative damage, altering the storage form, subcellular distribution of Cd in soybeans, and was more noticeable when combined overall (Si+Se＞Se＞Si). Si+Se increased root activity by 28% and CAT activity in leaves by 130.65%. Overall, the combined application of Si and Se exhibited a pronounced synergistic effect in enhancing the healthy growth of soybean plants under Cd pollution, with a more prominent impact observed following the second fertilization.