Induced Phytoextraction of Heavy Metals from Soils Using Brassica juncea and EDTA: An Efficient Approach to the Remedy of Zinc, Copper and Lead

Contamination of agricultural soils with heavy metals, such as zinc (Zn), copper (Cu) and lead (Pb), is a major problem for food safety and environmental sustainability. The present study aimed to evaluate the efficiency of phytoremediation induced with Brassica juncea (Indian mustard) and ethylenediaminetetraacetic acid (EDTA) in reducing the content of heavy metals in contaminated soils. The experiment was carried out in a greenhouse, using soil polluted with Zn, Cu and Pb, to which different treatments were applied, using: the biological method (Indian mustard only), the chemical method (EDTA in three concentrations: 0.5–1.0–2.0 mmol·kg−1) and the mixed method (Indian mustard and EDTA in three concentrations: 0.5–1.0–2.0 mmol·kg−1). The determinations included the analysis of the residual metal content by atomic absorption spectroscopy, as well as the evaluation of the physiological parameters of the plants (biomass, chlorophyll content in leaves, humidity, height). The results of unifactorial and bifactorial ANOVA revealed highly significant differences (p < 0.001) between the treatments and the types of metals, confirming the synergistic interaction between the chelation and phytoextraction processes. The combined treatments Indian mustard and EDTA in concentrations of 1.0 mmol·kg−1 and 2.0 mmol·kg−1, ensured the highest decontamination efficiency, with reductions of 51.5% for Zn, 36.3% for Pb and 27.5% for Cu. In conclusion, the mixed method represents a viable, ecological and reproducible strategy for the remediation of soils contaminated with heavy metals.