Abstract: Applying organic acids to improve the efficiency of phytoremediation becomes an effective approach for the remedy of heavy metals contaminated soils and waters. By the method of hydroponic culture, this paper studied the effects of EDTA and citric acid on the Cd and Cu accumulation and physiological characteristics of Iris pseudacorus L. under Cd and Cu stresses. The results showed that EDTA and citric acid promoted the absorption of Cd and Cu by I. pseudacorus, and enhanced the translocation of these two heavy metals from plant root to shoot. Citric acid had a higher promotion effect on the Cd absorption than EDTA, while EDTA promoted more Cu adsorption than citric acid. Different concentrations of EDTA and citric acid had different effects on the growth and physiological characteristics of I. pseudacorus, e.g., 5 mmol·L^-1 of EDTA and 0.5 and 5 mmol·L^-1 of citric acid decreased the dry mass of I. pseudacorus to a certain extent and increased the malondialdehyde (MDA) content significantly, while 0.5 mmol·L^-1 of EDTA not only increased the Cd and Cu accumulation and decreased the lipid peroxidation of I. pseudacorus, but also played an active role in the plant growth.

Key words: Quercus liaotungensis, Tilia paucicostata, Natural secondary stand, Evapotranspiration, Forest structure