Abstract: The effects of EDTA on Cu absorption， accumulation and physiological and biochemical parameters in Iris pseudacorus L. and Iris lactea var. chinesis（Fisch.）Roide were studied by hydroponic method. The results showed that addition of EDTA （0.28 and 0.55 mmol·L-1） relieved the toxicity of Cu （0.55 mmol·L-1） as indicated by the increased biomass of the two plant species compared with Cu treatment alone. However， under Cu stress， addition of 1.10 mmol·L-1 EDTA showed negative effect that the biomass of two plants decreased compared with 0.28 and 0.55 mmol·L-1 EDTA treatments. Addition of EDTA （0.28-0.55 mmol·L-1） promoted the transference of Cu from root to shoot in two plants. The highest total Cu accumulation of shoots of the two plants was observed in 055 mmol·L-1 EDTA treatment. The mitigating effect of EDTA on Cu stress was also showed by the increased contents of proline and decreased MDA contents in the leaves of Iris pseudacorus L. and Iris lactea var. chinesis（Fisch.）Roide. There was no significant effect when the concentration of EDTA was higher than 055 mmol·L-1, indicating that the accumulation of Cu in roots decreased, as well as the shoots. But higher concentration of EDTA（1.10 mmol·L-1） could lead to the decrease in biomass of two plant species, which showed that higher EDTA concentration could result in toxicity.

Key words: Iris pseudacorus L., Iris lactea var. chinesis（Fisch.）Roide, Cu stress, EDTA, physiological and biochemical parameter