Effect of spent mushroom substrate on strengthening the phytoremediation potential of Ricinus communis to Cd- and Zn-polluted soil.

Phytoremediation is a kind of efficient strategy for remediating soils polluted with heavy metals. The aim of this study was to investigate the influence of spent mushroom substrate (SMS) on the phytoremediation potential of Ricinus communis in Cd- and Zn-polluted soil. We treated the soil with SMS before growing plants and analyzed the contents, distribution of heavy metals, and response of plants after growth. SMS increased the contents of Cd (5%-13%) and Zn (16%-20%) in the cell wall. This finding suggested that high amounts of Cd and Zn were absorbed and bonded to the cell wall through metabolism adaption and formed stable compounds, which reduced the damage of the heavy metal to cells. SMS also decreased the levels of superoxide dismutase, peroxidase, and catalase by 9.5%-27.7%, 8.8%-30.0% and 8.5%-28.1%, respectively. Treatment of SMS alleviated the toxicity of heavy metal in plants and increased the extracted amounts of Zn and Cd by 101%-227% and 51%-189%, respectively. Hence, SMS treatment could reduce the toxicity of heavy metals to plants and strengthen the phytoremediation potential.