Evaluating the impact of arbuscular mycorrhizal fungi on the phytoremediation potential of Vetiveria zizanioides and Saccharum spontaneum on coal mine waste, India

Phytoremediation emerges as a sustainable, cost-effective, and eco-friendly solution for managing degraded sites. In this study, vetiver and Saccharum grasses were utilized for the phytoremediation experiment using coal mine waste (CMW) amended with farm soil and mycorrhiza ( Glomus hoi ) and growing them for 90 days. The results indicate that mycorrhizal amendment reduces stress in test plants, enhancing the metal tolerance index in both vetiver (295.45 ± 18.98 %) and Saccharum (212.50 ± 12.74 %). The plants grown in amended soil showed less malonaldehyde and antioxidative stress enzyme (catalase and guaiacol peroxidase) formation compared to the plants grown on only CMW and without amendment. The amendments significantly reduced the bioavailable fractions [T4 (Cr: 20.36 %, Ni: 22.60 %, Pb: 21.01 %), T8 (Cr: 11.19 %, Ni: 16.41 %, Pb: 18.14 %)] of heavy metals (HMs) in the potting mix. Initially, microbial parameters in the potting mix were very minimal but increased significantly after 90 days, with the highest levels observed in treatments T3, T4, T6, and T7. The bioaccumulation factor for roots was higher compared to the shoot. The translocation factor of HMs, except for Cu, were < 1 across different treatments, depicting restricted translocation to the shoot. Despite the higher HMs concentration in CMW, both vetiver and Saccharum spontaneum grass showed good growth in the amended potting mix, with vetiver proving superior in reducing the bioavailable HMs fractions. Partial least square structural equation modelling (PLS-SEM) highlighted vetiver’s (R 2 = 0.806) higher phytoremediation potential compared to Saccharum (R 2 = 0.962). Nevertheless, both species are recommended for phytoremediation of HMs from the CMW. • Coal mine waste was phyto-remediated by Vetiver and Saccharum grass. • Glomus hoi helped test-plants to combat heavy metal stress. • Vetiver performed rhizofiltration and phytostabilization. • Saccharum sp. helped through phytoextraction. • PLS-SEM identified Vetiver has high phyto-remedial potential.