New approach of antioxidant properties of Zinnia elegans using bioremediation of Pb-contaminated soils

Abstract There is little information on the impact of soil amendments on lead absorption by ornamental plants as phytoremediation and the antioxidant system. The experiment was set up in a factorial based on completely block design with three replications on Zinnia elegans. [Pb (NO3) at (0, 40, 80, and 120 mg kg−1), soil amendment (control, diethylene trinitrilo pentaacetic acid (DTPA) 2.5 mM, DTPA 5 mM, humic acid 200 mg. L−1, and HA 400 mg. L−1)]. Increased Pb concentration resulted in a significant rise in antioxidant enzymes, as well as an increase in Pb absorption by Z. elegans. DTPA 5 mM and HA 400 mg. L−1 application lead to significantly higher shoot dry weight (49 and 56%), root dry weight (62 and 63%), catalase (CAT) (18 and 19%), peroxidase (POX) (63 and 67%), superoxide dismutase (SOD) (10 and 14%), and shoot Pb (36 and 33 mg.kg−1) in the contaminated soil, respectively. With the application of DTPA and HA, the residual Pb in soil fell in a negative association with the remediation factor. Z. elegans growing in polluted soils treated with DTPA 5 mM and HA 400 mg. kg−1 showed Pb tolerance by inducing an effective antioxidative response to Pb toxicity and enhancing Pb absorption for phytoremediation purposes.