Evaluation of multiple applications of EDTA and LMWOAs on phytotoxicity and phytoextraction of Zn, Cd, Pb and Cu in soil with Tagetes sp.

Abstract

Phytorextraction using chelating agents has been developed to enhance the accumulation of trace elements (TEs) by high biomass plants. Synthetic chelates like ethylenediaminetetra acetic acid (EDTA) is most effective to solubilize the TEs in the soil solution and inrease the accumulation in the plants. However, the excessive amount of TEs solubilized by EDTA in the soil can decrease the growth and biomass of plants and increase environmental risk. Low molecular weight organic acids (LMWOAs), on the otherhand are used for enhancement of phytoextraction. However, LMWOAs are less and/or not effective as these are easily biodegradable and hence there is re-precipitation and/or reabsorbtion of TEs on soil particles. In this study, we compared the performance of multiple application of EDTA with LMWOAs in enhancing phytoextraction of TEs and phytoxic effects on Tagetes sp., spiked in multimetal contaminated soils. It was observed that multiple application of LMWOAs were able to enhance the accumulation of Zn, Cd, Pb and Cu without any toxic effect on plants. Net accumulation of TEs by EDTA was higher as compared to LMWOAs, but multiple application of EDTA could not minimised the toxic effect on plants.