Mitigation of Chromium‐Induced Oxidative Stress in Lemongrass Cultivated on Sukinda Chromite Mine Overburden Soil Through Bagasse Biochar Amendment

ABSTRACT

This study evaluates the effectiveness of sugarcane bagasse biochar (SBB) in mitigating chromium (Cr)‐induced oxidative stress in Cymbopogon flexuosus (lemongrass) grown on overburden soil (OBS) collected from a chromite mining site. The aim is to determine how SBB improves soil properties, reduces Cr toxicity, and enhances plant physiological and antioxidant responses for sustainable mine soil remediation. A greenhouse experiment was conducted with five treatments: T1 (garden soil), T2 (OBS), and T3–T5 (OBS with 5%, 10%, and 15% SBB). Soil physicochemical parameters (pH, organic carbon, cation exchange capacity (CEC), electrical conductivity), plant stress indicators (relative water content, electrolyte leakage), and reactive oxygen species (superoxide radicals (O ₂ • ⁻ ), hydrogen peroxide (H ₂ O ₂ ), malondialdehyde (MDA)) were quantified. Antioxidant enzyme activities ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), non‐enzymatic antioxidants (AsA, GSH), and soil enzyme activities were measured to assess biological responses. OBS showed poor fertility and elevated Cr levels. SBB amendments significantly improved soil quality by increasing pH, organic carbon, CEC, and soil enzyme activities. Cr accumulation in shoots and roots was lowest under 10% SBB treatment, indicating more effective restriction of Cr uptake at this dose. However, 15% SBB showed improvement in soil physicochemical properties, antioxidant activity, relative water content, and reduction of oxidative stress markers, suggesting superior overall stress mitigation despite slightly higher Cr accumulation than 10% SBB. Antioxidant defense mechanisms were strongly enhanced, reflected in increased APX, GR, MDHAR, AsA, GSH, and improved redox ratios. SBB effectively ameliorates Cr‐contaminated OBS, reduces the Cr accumulation, enhances plant physiological resilience, and strengthens antioxidant systems. The findings demonstrate that SBB is a promising, eco‐friendly, and cost‐effective amendment for restoring Cr‐polluted mine soils and promoting sustainable cultivation of aromatic grasses on degraded lands.