Exogenous application of ethylenediamminetetraacetic acid enhanced phytoremediation of cadmium by Brassica napus L.

Performance of B. napus in phytoextraction—an in situ environment friendly technique for the cleanup of contaminated soils—was evaluated through its response to cadmium (Cd) toxicity in combination with a chelator ethylenediamminetetraacetic acid (EDTA) while growing hydroponically in greenhouse conditions under three levels of Cd (0, 10, and 50 µM) and two levels of EDTA (0 and 2.5 mM). Cadmium presence decreased plant growth, biomass and chlorophyll concentrations, while the application of EDTA enhanced plant growth by reducing Cd-induced effects in Cd-stressed plants. Addition of EDTA improved the net photosynthetic and gas exchange capacity of plants under Cd stress. Presence of Cd at 10 and 50 μM significantly increased electrolyte leakage, the production of hydrogen peroxidase (H₂O₂) and malondialdehyde (MDA) resulting into a significant reduction in the activities of catalase, guaiacol peroxidase, ascorbate peroxidase and superoxide dismutase in Cd-stressed plants. Application of EDTA at the rate of 2.5 mM alone and with combination of Cd increased the antioxidant enzymes activities and reduced the electrolyte leakage and production of H₂O₂ and MDA. The B.napus actively accumulated Cd when applied with EDTA in roots, stems and leaves viz. 2817, 2207 and 1238 mg kg⁻¹ DW, respectively, at higher Cd level (50 μM) followed by lower level of Cd (10 μM) viz. 1704, 1366 and 763 mg kg⁻¹ DW, respectively. Results showed that this technique could be useful for the remediation of heavy metal-contaminated agricultural and industrial soils.