EXOGENOUS ORGANIC ACIDS PROTECT CHANGBAI LARCH (LARIX OLGENSIS) SEEDLINGS AGAINST CADMIUM TOXICITY

摘要

This work focused on the beneficial role of exogenous organic acids (0.2, 1.0, 5.0 and 10.0 mmol/L oxalic acid and citric acid) in protecting Changbai larch (Larix olgensis) seedlings exposed to 10 mg/kg Cd for 10, 20 and 30 days against cadmium (Cd) toxicity, and alleviating Cd-induced oxidative injuries. Exposure to 10 mg/kg Cd had harmful effects on Larix olgensis seedlings. Lipid peroxidation and electrolyte leakage significantly increased in leaves, malondialdehyde (MDA) content and relative conductivity increased, superoxide dismutase (SOD) and peroxidase (POD) activities, proline, soluble protein, and chlorophyll contents all decreased, while Cd contents in fine roots and leaves significantly increased. And the toxicity increased with increasing Cd exposure time. When Cd-treated plants were exposed to oxalic acid or citric acid (especially 5.0 or 10.0 mmol/L for 20 or 30 days of treatment), the effect of Cd treatment on above physiological parameters was reversed, Cd absorption and accumulation in fine roots and leaves decreased, while seedling height and ground diameter significantly increased; citric acid was more effective than oxalic acid. The results showed that exogenous organic acid treatments alleviated Cd-induced oxidative injuries and protected Larix olgensis seedlings against Cd toxicity.