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

Abstract

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.