Abstract: To optimize the fermentation conditions of Trichoderma yunnanensis, which has antagonistic effect on Colletotrichum camelliae, single factor and response surface tests were performed with the inhibition rate of C. camelliae as the evaluation index. Then, the antagonistic activity, in vitro leaf control effect, indoor pot control effect, and growth effect of the fermentation broth on C. camelliae and tea plants, respectively, were determined. The results show that the optimum fermentation conditions of T. yunnanense were as follows: potato 200βg·L^-1, mannitol 18.85βg·L^-1, yeast extract 4.73βg·L^-1, liquid content 372.60βmL·L^-1, culture temperature 25β℃, pH 6.6, 12L∶12D. The inhibitory rate of the obtained fermentation broth on C. camelliae reached 92.61% under the ratio of 1∶9 mixed with potato broth (PDA) medium. The control effect of the fermentation broth on anthrax in vitro leaf was 63.71% and that on indoor potted tea plants was 68.95%, both of which were significantly higher than that of T. harzianum wettable powder and carbendazim. Compared with the water control, the growth of tea seedlings treated with fermentation solution of T. yunnensis was significantly improved, which was manifested by the increase of root length, root fresh weight, plant height and above ground fresh weight by 69.16%, 215.70%, 42.13% and 212.11% respectively. Overall, T. yunnanense fermentation liquid has both antibiotic and growth-promoting effects. The results provided a theoretical basis for the application of T. yunnanense fermentation broth in the biological control of tea anthracnose.

Key words: Trichoderma yunnanensis, tea anthracnose, fermentation broth, response surface method, biological control