The combined phytoremediation strategy using arbuscular mycorrhizal fungi, rhizobia, and biochar enhances lead tolerance and growth of white clover (Trifolium repens L.)

Phytoremediation is reliably used to remediate heavy metal-contaminated soils as a green technology. This study evaluates a synergistic approach using arbuscular mycorrhizal (AM) fungi, rhizobia (Rh), and biochar to remediate lead (Pb)-contaminated soils. Trifolium repens Linn. was used in a pot experiment with treatments using different combinations of AM fungi, Rh, and biochar. The results indicate that a combination of moderate biochar (5%-10% w/w) and dual inoculation enhanced plant growth, biomass, and root development while also mitigating the inhibitory effects observed at a higher biochar dosage (15%). Treatment with 10% biochar and dual inoculation achieved the greatest Pb immobilization by reducing root Pb content by 78.4%, restricting Pb translocation to shoots, and improving plant nutrient acquisition, especially nitrogen (N) and phosphorus (P). The combined treatment enhanced plant growth, improved N and P acquisition, upregulated key metabolic enzymes, and strengthened antioxidant defenses. Multivariate analyses revealed strong negative correlations between roots P and carbon (C) contents and Pb accumulation, supporting a rhizosphere-level immobilization mechanism. This study demonstrates a practical and sustainable biochar-microbe-plant synergy that reduces Pb toxicity, enhances plant growth, and benefits long-term soil health. These results offer a potential approach for remediating Pb-contaminated fields while supporting environmental quality and resource recycling.