Optimization of Citric Acid and EDTA Levels Under Ni Stress Using Rapeseed Brassica napus L. for Phytoremediation

Heavy metals like nickel, cadmium, and chromium found in industrial waste pose a serious threat to living organisms. Nickel is extremely poisonous and causes numerous human ailments when it is exceeded from the permissible limit. The most efficient and cost-effective method of removing nickel from contaminated soil is phytoremediation and chelating agents act as supporting material for phytoremediation. Consequently, the purpose of the current study was to enhance the phyto-extraction potential of Brassica napus by using chelating agents such as citric acid and ethylene diamine tetra acetic acid (EDTA). For phytoremediation, experimental treatments were comprised of different levels of citric acid, i.e., 10 mM and 20 mM and EDTA, i.e., 1.5 mM and 2.0 mM and the combinations of both (citric acid + EDTA), i.e., 10 mM + 1.5 mM, 20 mM + 1.5 mM, 10 mM + 2.0 mM, and 20 mM + 2.0 mM respectively under Ni toxicity. A control without citric acid and EDTA was kept for comparison. Different growth, physiological, and biochemical attributes were measured and analyzed statistically. Results revealed that the concentration of citric acid (10 mM) and EDTA (1.5 mM) separately and in combination EDTA (1.5 mM) + citric acid (10 mM) performed better for the purpose of phytoremediation and accelerate phytoextraction of Ni through hyper-accumulated Brassica napus. Highest Ni content (27.33 mg/kg) were observed in plants of Corn-II receiving EDTA followed by CA treatment (24.33 mg/pot) and combined EDTA + CA treatment (24.85 mg/pot). The ability of Rapeseed to bio-accumulate heavy metals can be used to reduce the level of contaminants in the soil making it suitable for the cultivation of other metals sensitive food crops. The current work demonstrates the effective application of chelating agents (CA and EDTA) to reduce Ni stress as well as to increase Ni accumulation, a requirement for phytoremediation. It is suggested that B. napus species can be utilized for phytoremediation as it is a good accumulator of Ni and other metals.