Abstract: The effects of silicon on the phenols metabolism in Avicennia marina seedlings were studied under the stress of cadmium by adopting the hydroponic method, and the effects of silicon on the resistance of A. marina seedling to cadmium were further explored. The results showed that under the stress of cadmium of low concentration (Cd 0.5 mg·L^-1), the content of malondialdehyde in the leaves and roots decreased with the increase of the exogenous silicon level, and the total phenol content in each organ was the highest at Si 50 mg·L^-1, while the effect of silicon on the tannin content in each organ was not significant. The highconcentration cadmium (Cd 5 mg·L^-1) led to the membrane lipid peroxidation of the leaves and roots in A. marina, making the content of malondialdehyde significantly higher than that of the control; the addition of the exogenous silicon significantly reduced the accumulation of malondialdehyde in the leaves and roots of A. marina, and Si 100 mg·L^-1 significantly increased the contents of total phenol and tannin in each organ. Significant negative correlations between the malondialdehyde content and total phenol content in roots and between the malondialdehyde content and tannin content in leaves were found, indicating that silicon significantly stimulated phenolic metabolism in A. marina organs under the stress of highconcentration cadmium, increased the oxidation resistance of the root system and leaves, and thus increased the tolerance of A. marina to cadmium.

Key words: landscape pattern, Nansihu Lake basin., landscape pattern vulnerability