Abstract: To screen plants that can tolerate and accumulate high levels of Pb, Zn and Cd compound heavy metals, a pot experiment was conducted with seven combination concentrations of Pb, Zn and Cd. The response of antioxidant enzymes (SOD, CAT, POD) and other physiological indicators (MDA and Pro) in leaves of Symphytum officinale, Ricinus communis, and Lolium perenne under the stress of Pb, Zn and Cd compound pollution were examined. The enrichment characteristics （enrichment amount, bioaccumulation factor (BCF), and translocation factor (TF)） for Pb, Zn and Cd in different parts of three species were observed. The results showed that SOD of S. officinale and R. communis increased with intensified composite stress of Pb, Zn, and Cd. The SOD of L. perenne increased first and then decreased. The CAT of S. officinale and L. perenne showed the “hormesis effect”. The CAT of R. communis decreased gradually. The POD of S. officinale and L. Perenne decreased first and then increased. The POD of R. communis increased first, then decreased and then increased. The MDA of S. officinale showed a decreasing trend. The MDA of R. communis showed an increasing trend. The MDA of L. perenne was small. The Pro of R. communis and L. perenne showed a pattern of first rising and then falling, while that S. officinale showed a gradually decreasing trend. In general, the SOD, CAT, POD, MDA, and Pro of the three species differed across the concentration gradient (P<0.05). Based on the enrichment characteristics of Pb, Zn and Cd in the three species, the enrichment amount, BCF and TF of S. officinale for Pb, Zn, and Cd simultaneously achieve the limit requirements of each index of hyperaccumulator. S. officinale is a potential hyperaccumulating species for Pb, Zn and Cd complex heavy metals and can be used as a preferred plant for remediation of Pb, Zn and Cd contaminated soil.

Key words: heavy metal, hyperaccumulator, soil remediation, phytoremediation, stress response