Abstract: The induction of defense enzymes activities and control effect of Phytophthora root rot by Trichoderma longibrachiaum T115D were measured by UV spectrophotometry and investigated by flowerpot experiments. The results showed that the activity of PAL, POD, PPO, SOD and CAT in the soyben leaves was improved after induction by fermentation broth of T115D. The five enzymes activities were of longer duration and higher peaks than those of the control treatment by Phytophthora sojae. When soyben leaves were first treated with spores in fermentation broth of T115D and then inoculated with P. sojae at the 2^nd d, induced effect of defense enzymes activities was the best at the 5^th day, and the activities of PAL, PPO, POD andCAT reached the maximum, which were 2.5, 6.6, 4.8 and 3.5 times as those of the petri culture liquid control, respectively. Different treatments of T115D fermentation broth could reduce the occurrence of phytophthora root rot. Among the spray treatments, when soyben leaves were first treated with fermentation broth of T115D by spray and then inoculated with P. sojaeat the 2^nd d, control effect on phytophthora root rot was the best with the efficacy of 73.3%, which was significantly higher than that of other treatments. Among the root-dreaching treatments, when soyben were treated at the same time with spores in fermentation broth of T115D and P. sojae by root drenching, control effect was the best with the efficacy of 51.8%, which was significantly higher than that of other treatments. Among the treatments with different inoculation amount of T115D fermentation broth by root-drenching, control effect of spores in 15 mL fermentation broth was the highest with the efficacy of 70.9%.

Key words: Trichoderma longibrachiatum, Phytophthora root rot, defense enzymes, control effect in flowerpot