Abstract: A study has been undertaken to investigate the effects on Elymus dahuricus of different concentrations (1,2,4 mmol·L^-1) of exogenous citric, malic and oxalic acids on the biomass, Cd content in above-ground plant and root, and changes in morphological parameters and plant growth. Pot culture tests were carried out under Cd stress to reveal how organic acids affect the absorption, transport and accumulation of Cd. The main results are as follows. When treated with Cd₅₀, plant height, root length and biomass significantly reduced (P<0.05). The three exogenous organic acids could increase the content of Cd and biomass in the roots and shoots of E. dahuricus. In terms of cadmium accumulation, oxalic acid had the strongest effects; under Cd₅₀+OA₂ treatment conditions, the E. dahuricus translocation coefficient was 1.38 and Cd concentration in shoots reached the maximum value of 268.511 μg·plant^-1. On the other hand, from the point of view of improving plant growth, the citric acid treatment performed best; under Cd₅₀+CA₄ treatment conditions, the root and shoot biomass were 1.82 and 1.53 times higher than that of Cd₅₀. Comprehensive analysis shows that the three exogenous organic acids can strengthen Cd-contaminated E. dahuricus. The use of these acids is likely to be an effective way to improve the phytoremediation efficiency of soils contaminated by heavy metals.

Key words: Elymus dahuricus, organic acid, Cd stress, phytoremediation