Unlocking Soil Remediation Potential: Effects of Chelators on Moringa oleifera Lam. Growth and Soil Health in Heavy Metal Contamination

T he study investigated the effects of EDTA and citric acid on the growth, soil physicochemical properties, and heavy metal concentrations in Moringa oleifera Lam. (Moringaceae) cultivated in polluted soils. Chelator-treated plants exhibited enhanced growth metrics compared to the control. EDTA at 0.5 g kg-1 soil resulted in a shoot fresh weight of 30.33 g and a root fresh weight of 21.86 g, significantly higher than the control. Citric acid at 1.0 g kg-1 soil also showed substantial improvements, with a shoot fresh weight of 31.66 g and a root fresh weight of 35.33 g. Chelators modified soil pH and electrical conductivity. EDTA treatments led to slightly lower pH values. The concentrations of extractable heavy metals increased with chelator treatments. EDTA at 1 g kg-1 soil reduced Zn from 135.49 mg kg-1 in the control to 52.62 mg kg-1 , Ni from 112 mg kg-1 to 53.44 mg kg-1 , and Pb from 154.23 to 82.39 mg kg-1 . Citric acid at 1 gm kg-1 soil resulted in Zn concentrations of 115.76 mg kg-1 , Ni of 63.99 mg kg-1 , and Pb of 116.01 mg kg-1 . The concentrations of heavy metals in the roots and shoots of Moringa increased with higher chelator concentrations. EDTA treatments were more effective than citric acid in enhancing metal uptake, especially for Pb. Phytochemical analysis showed that both citric acid and EDTA treatments boosted total phenolics, alkaloids, and flavonoids in Moringa. These findings suggest that both chelators can mitigate heavy metal stress and enhance phytoextraction efficiency, with EDTA generally outperforming citric acid in terms of growth enhancement, heavy metal uptake, and phytochemical enrichment.