Abstract:

In order to clarify the effects of aluminum stress on active oxygen metabolism and membrane system, the seedlings of Longan (Dimocarpus longan)cultivated in nutritional solution were studied under the condition of aluminum stress. The results showed as follows: The cell membrane and defense system of AOS were damaged by aluminum stress. The aluminum stress caused membrane lipid peroxidation and increment of permeability of plasma membrane. Compared with CK, the content of MDA increased 5.85%～89.54%, and the leakage value of K⁺ 12.16%～132.35%, the leakage value of macromolecules 10.43%～100.08%. The reason for membrane lipid peroxidation was the accumulation of O^-·₂、H₂O₂. The producing rate of O^-·₂ was enhanced 44.49%～443.48%, and the content of H₂O₂ 0.62%～58.36% under aluminum stress. And the reason for the accumulation of AOS, such as O^-·₂,H₂O₂,was that aluminum stress damaged the harmony of cell's protective enzyme and antioxidational substances. In addition, the activities of SOD, POD, and GR were enhanced as the concentration of aluminum increased , and they reached to the maximum when the concentration of aluminum was 0.370 mmol·L^-1. However, they decreased as the concentration of aluminum increased continually. The study also indicated that the activity of CAT decreased and the AsA-POD increased gradually under aluminum stress. Aluminum stress also reduced the content of AsA. The content of GSH increased as the concentration of aluminum was enhanced. And it reached to the maximum as the concentration of aluminum was 0.740 mmol·L^-1, then it decreased when the concentration was enhanced continually.

Key words: Longan (Dimocarpus longan), Aluminum stress, Active oxygen metabolism, Membrane system