Bio-remediation of Pb and Cd polluted soils by switchgrass: A case study in India

ABSTRACT

Introduction: In the present study bioremediation potential of a high biomass yielding grass, Panicum virgatum (switchgrass), along with plant associated microbes (AM fungi and Azospirillum), was tested against lead and cadmium in pot trials.

Methods: A pot trial was set up in order to evaluate bioremediation efficiency of P. virgatum in association with PAMs (Plant Associated Microbes). Growth parameters and bioremediation potential of endomycorrhizal fungi (AMF) and Azospirillum against different concentrations of Pb and Cd were compared.

Results: AM fungi and Azospirillum increased the root length, branches, surface area, and root and shoot biomass. The soil pH was found towards neutral with AMF and Azospirillum inoculations. The bioconcentration factor (BCF) for Pb (12 mg kg⁻¹) and Cd (10 mg kg⁻¹) were found to be 0.25 and 0.23 respectively and translocation index (Ti) was 17.8 and 16.7 respectively (approx 45% higher than control).

Conclusions: The lower values of BCF and Ti, even at highest concentration of Pb and Cd, revealed the capability of switchgrass of accumulating high concentration of Pb and Cd in the roots, while preventing the translocation of Pb and Cd to aerial biomass.

KEY WORDS:

• Bioremediation
• biofuels
• PAMs
• Endomycorrhizal fungi
• Azospirillum

Acknowledgment

This work was supported by the European Commission under the project OPTIMA, “Optimization of Perennial Grasses for Biomass Production in the Mediterranean Area” G.A. No 289642.