Utilization of Parthenium hysterophorus for the remediation of lead-contaminated soil

A greenhouse experiment was conducted to study the role of plant growth regulators, a chelating agent, and plant growth-promoting bacteria in lead (Pb) phytoextraction and their subsequent effect on the weed plant, Parthenium hysterophorus. Gibberellic acid (GA(3)) and indole-3-acetic acid (IAA) were used as the foliar spray. Ethylenediamine tetra acetic acid (EDTA) was applied in split doses. Bacillus and Rhizobium strains were used as a single culture and as co-culture. The accumulation of Pb in different parts of the plant was analyzed by using an atomic absorption spectrophotometer. The amount of lead translocation and accumulation in the stems and leaves was significantly higher in the hormonal and EDTA treatments, while the microbial treatments showed no significant difference in the amount of Pb translocation into the stems and leaves, when compared to the control. The EDTA increased the amount of translocation into the shoots, but the dry biomass declined and subsequently reduced the total Pb phytoextraction. The GA3 treatment showed the maximum total Pb accumulation, along with a higher dry biomass. The microbial co-inoculated plants showed a significant increase in their dry biomass but the Pb accumulation did not increase like with the GA3 and IAA treatments. These findings encourage the use of the GA3 application for Pb phytoextraction by P. hysterophorus. One important feature of this weed plant is its unpalatable nature to herbivores, which could help in reducing the entrance of Pb into the food chain. Gibberellic acid is environmentally friendly compared to EDTA; therefore, more investigation of GA3 and P. hysterophorus is required.