Alleviation Of Exogenous ABA On Cadmium Toxicity Of Oryza Sativa L.

Cadmium(Cd) was a heavy metal of high toxicity and existed diffusely in environment. It exerted a wild range of adverse effects on plants and even the healthy of animals and human beings by food chains. Abscisic acid (ABA) considered as an basilic phytohormone, played an important role in the regulation of plant growth and development. It appeared that ABA was a general endogenous inducer of tolerance to environment stresses and significantly increased freezing, chilling, drought , and salt tolerance by activating the anti-adverse stress system.The possible effects of exogenous ABA on alleviating cadmium toxicity and the antioxidant enzymes metabolizing on rice seedlings were studied. Seedlings of Oryza Sativa L. (Xiushui 110) were cultured hydroponically, and then were exposed to 0.25mmol·L^-1 Cd after pre-treatment with 1.00 mg·L^-1 ABA. The results showed, after Cadmium exposure, rice seedlings grew more weakly than the contrast group. Compared with the group without ABA pre-treatment , the ABA pre-treatment group was of less chlorosis and lower Cadmium accumulation, especially in the shoot. The fresh weight, chlorophyll content and soluble protein content in leaves of rice seedlings with ABA pre-treatment were significantly higher than in seedlings without ABA pre-treatment at the same Cd intensity. Moreover, activities of protective enzymes(SOD, POD) enhanced and the content of H₂O₂ in leaves of seedlings were reduced. So it was concluded that ABA could alleviate the toxic effects caused by Cd²⁺ stress.