Toxic effects of heavy metals (CU, ZN, PB, CD) on early growth of three tagetes species

Abstract

Objective: Heavy metals in soil pose potential threats to the environment, therefore remediation of heavy metal contaminated sites is an important issue. Tagetes species have been proposed as potential plants for phytoremediation of heavy metal contaminated soil. Although much research has been carried out previously to investigate the bioaccumulation ability of Tagetes species, little information is available on the toxicity of metals on these plants. Therefore, our objective was to investigate the toxic effects of heavy metals on these plants. Methods: In our study a seed germination test was conducted to measure the toxic effects of four heavy metals (Cu, Zn, Pb and Cd) on early growth of three different Tagetes species (Tagetes erecta, Tagetes patula and Tagetes tenuifolia). Results: Our results showed that all tested heavy metals had significant (p<0.05) toxic effects on seed germination and root/shoot elongation of the three plants. On the basis of IC50 values (concentration of a heavy metal which causes 50% inhibition) the following series of phytotoxicity was observed: Cd>Cu>Zn>Pb.