Assessment of Phytoremediation Potential of Seven Weed Plants Growing in Chromium- and Nickel-Contaminated Soil

Abstract

A pot experiment was conducted to evaluate the phytoremediation efficacies of seven weed plant species, viz., Bidens pilosa L., Chenopodium album L., Malvastrum coromandelianum L., Garcke, Oxalis corniculata L., Parthenium hysterophorus L. (an invasive species), Polypogon monspeliensis L., and Rumex dentatus L., against heavy metals like chromium (Cr) and Nickel (Ni). These metals were administered in dose ranges from 10 to 40 mg CrNO3 and 10 to 50 mg NiNO3 kg–1 soil. Biochemical parameters like total chlorophyll, carotenoids, protein, and proline contents were measured against metal stress. Uptake parameters, viz., bioconcentration factor (BCF), bioaccumulation coefficient (BAC), and translocation factor (TF), were also evaluated. Remediation potential of experimental plants was judged based on tolerance index (TI). All plants, when treated with Ni10–20 and Cr10 enhanced total chlorophyll and carotenoid contents. Increase in contamination and enrichment ratio caused a toxic response to plants up to some extent. Ni and Cr stress decreased the protein content and increased proline content in a concentration-dependent manner. Plant species invariably showed high TI at the lowest dose and low TI at higher doses of both heavy metals. A significant increase in Cr and Ni accumulation, coupled with a high bioaccumulation coefficient, in roots and shoots of all seven species was observed as a response to Cr and Ni stress.