Phytoremediation of Heavy Metal Contaminated Soil Using Bidens pilosa: Effect of Varying Concentrations of Sophorolipids.

The current study investigates the impact of biosurfactant (sophorolipids, SL) concentrations (0.1 to 1 g kg -1 ) on the removal of cadmium (29 mg kg -1 ) from soil using Bidens pilosa. The results showed that increasing concentrations of SL increased the plant biomass. The dry weight of plants was 0.87 g, 0.77 g, 0.65 g, 0.85 g, 0.91 g, 0.92 g, 1.06 g in control, SL 0 (No SL), SL 1 (0.1 g kg -1 ), SL 2 (0.25 g kg -1 ), SL 3 (0.5 g kg -1 ), SL 4 (0.75 g kg -1 ), and SL 5 (1 g kg -1 ), respectively. It was observed that root length was higher in SL augmented soil in comparison to treatments without SL. It was also found that, with increasing the SL concentration, total chlorophyll and proline concentrations increased as well. The SL 2 treatment had the highest Cd accumulation (76.33 µg pot -1 ) in the plant. Therefore, SL at 0.25 g kg -1 was considered the most effective concentration for the phytoextraction of Cd from soil. Soil enzyme activities, i.e., alkaline phosphatase, dehydrogenase, and urease activity, increased with the increase in SL concentration. The results of this study concluded that SL promotes the removal of Cd from soil and supports plant growth as well as enzymatic activities in soil.