Comparative analysis of ethylenediaminetetraacetic acid and citric acid for enhanced lead phytoremediation in wheat and maize plants

Abstract

Heavy metal contamination, particularly lead (Pb), threatens food safety and ecosystems. Phytoremediation using chelating agents like ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) can enhance metal uptake in plants. This study compared EDTA and CA in improving Pb phytoremediation efficiency in the non-edible parts of wheat and maize under Pb stress (500 and 800 ppm) with 500 ppm chelators. Growth parameters, photosynthetic pigments, and Pb accumulation in various parts of the plants were analyzed. Lead stress reduced shoot length by 26 % in wheat and 35 % in maize at 800 ppm, while CA restored shoot lengths to 85 % (wheat) and 88 % (maize), outperforming EDTA. CA increased fresh weight by 33 % and 28 % in wheat and maize, respectively, at 800 ppm. Photosynthetic pigments in CA-treated plants were 25–30 % higher than EDTA-treated plants under high Pb stress. CA enhanced accumulation, with maize roots accumulating 370 mg kg⁻¹ (Pb500 + CA) vs. 353 mg kg⁻¹ (Pb500 + EDTA). CA increased Pb in maize and wheat roots by 23 % and 18 % respectively as compared to EDTA. PCA revealed that 56.4 % of variance was expressed by three components, with PC1 (29.9 %) strongly correlating growth parameters with Pb uptake. Negative correlations (r = −0.78 to −0.82, p ≤ 0.05) between Pb accumulation in grains and growth metrics highlighted the role of CA in reducing edible part contamination. These findings demonstrate the superior efficacy of CA over EDTA in mitigating Pb toxicity, enhancing phytoremediation, and improving crop resilience, advocating its use for sustainable remediation of Pb-contaminated soils.