Amendment of biochar and thiourea-modified biochar to mitigate chromium bioavailability and toxicity by modulating oxidative stress system in Vigna radiata in chromium-contaminated agriculture soil
摘要
Chromium (Cr) contamination in agricultural soil poses a significant threat to crop productivity and human health. However, strategies to reduce Cr bioavailability and transfer within the soil–plant system remain limited. The sole application of biochar or Thiourea has been reported to mitigate Cr-induced toxicity in plants. However, the combined application of biochar and thiourea for alleviating Cr toxicity in plants and inhibiting Cr mobility in soil has not yet been reported. Therefore, this study examines the impact of biochar and thiourea biochar amendments on soil fertility and Cr stress tolerance in Vigna radiata. Biochar, derived from corn husk, was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS). Physicochemical properties, including pH (9.62 ± 0.109), salinity (0.91 ± 0.005 ppt), and EC (0.859 ± 0.021 mS/cm), were higher in thiourea biochar. FTIR revealed new peaks at 617.9 cm−1 and 1110.5 cm −1 in thiourea biochar, indicating successful thiourea modification. XRD and SEM analyses confirmed structural changes and increased porosity in thiourea biochar. In this study, a pot experiment was conducted in a completely randomized design with three replications (control, 25 mg kg−1 of Cr contamination soil, 25 mg kg−1 of Cr soil with 5% of biochar, and 25 mg kg−1 of Cr-contaminated soil with 5% of thiourea biochar) to study the mitigating effect of thiourea biochar on V. radiata growth and stabilization of Cr bioavailability. A randomized pot experiment showed that Cr (25 mg/kg) treatment alone reduced seed germination and plant growth, while thiourea biochar significantly enhanced seed germination (86.0%), shoot length (8.7 ± 0.173 cm), root length (4.01 ± 0.031 cm), and biomass (0.314 ± 0.002 g and 0.386 ± 0.001 g). Cr accumulation in V. radiata roots and shoots decreased significantly with thiourea biochar, and Cr translocation from root to shoot was reduced by 35.5%. Photosynthetic pigment content decreased by 20.0% under Cr stress and increased by 123.8% with thiourea biochar addition. Antioxidative enzyme activities catalase (CAT), peroxidase (POX), and superoxide (SOD) dismutase decreased under Cr stress but were significantly enhanced with thiourea biochar. Thus, thiourea biochar amendment in Cr-contaminated soil is an efficient strategy to promote plant growth, reduce Cr bioavailability, and thereby protect the ecosystem.