Citrus Epicarp-Derived Biochar Reduced Cd Uptake and Ameliorates Oxidative Stress in Young Abelmoschus esculentus (L.) Moench (okra) Under Low Cd Stress

Due to the important role of biochar (BC) in reducing metal-toxicity in plants, this study was aimed at assessing the potential of citrus epicarp-derived BC in ameliorating Cd toxicity in young Abelmoschus esculentus (okra) under low Cd toxicity. Okra was grown in soil amended with BC at four treatment levels for 49 days as follows: control (A), sole 1.4 mg Cd/kg-spiked soil (B), 1.4 mg Cd/kg-spiked soil + 1% BC (C) and 1.4 mg Cd/kg-spiked soil + 3% BC (D). The results showed a dose-dependent reduction in shoot accumulation of Cd due to the BC application. In addition, compared to control and sole Cd-amended soil, BC treatments (both at 1% and 3% w/w) decreased the oxidative stress, and enhanced activities of enzymatic and non-enzymatic antioxidants in the young okra. Generally, the application of BC to the soil was effective in ameliorating the Cd-induced oxidative stress in okra with limited shoot bioaccumulation of Cd.