Abstract: Antagonistic culture and growth inhibition were used to assess the inhibiting effects of Trichoderma virens T43 on S-phaeropsis sapinea, Cytospora chrysosperma, Rhizoctonia solani and Fusarium oxysporum. The impacts of ethyl acetate extract of T. virens T43 fermented liquid on the protective enzymes (CAT, POD and SOD) and osmotic adjustment substances (soluble protein, soluble sugar and MDA) of pathogens were used to analyze the inhibition mechanism of T43 on the pathogens. The results showed that T43 and its metabolites significantly inhibited the pathogens. The ethyl acetate extract reduced the activities of protective enzymes in pathogens, with SOD activity decreasing most significantly. The extract also significantly reduced the soluble sugar and protein contents, and increased the MDA content in pathogens, hence destroying cell integrity. This may be one of the inhibiting mechanisms of ethyl acetate extract of fermented liquid of T43 on the growth of pathogens.

Key words: Chinese fir plantation, height-diameter model, nonlinear mixed-effect model, stand variables