Cultural Characteristics of Trichoderma harzianum and its Inhibition to Phytophthora nicotianae

Trichoderma harzianum is one kind of important biocontrol agent against plant diseases. The T.harzianum TH-1 is an active antagonistism against Phytophthora nicotianae. The cultural characteristics of TH-1 on 4 artifical media and its inhibition of P.nicotianae were studied. The data showed that it grew faster and produced more spores on PDA than on the other media. Its optimum growth temperature ranged from 27.5℃ to 32.5℃ and the optimum initial pH was 5. Illumination had no influence on hyphae growth but it can stimulate sporulation. The pathogen growth of P.nicotianae was suppressed obviously by TH-1 in dual cultures. The results of the zoospore germination experiment showed that the cell-free filtrate of TH-1 can obviously suppress the zoospore's germination and extention of the pathogen, the inhibition rate was 12.7% and 63.1% respectively. High enzymatic activity of β-1,3-glucanases and cellulases produced by TH-1 was detected,which can degrade the cell wall of the plant pathogenic fungus. The results of metabolites determination showed that the Trichoderma isolate produced non-volatile antibiotics to suppress the germination of zoospore of P. nicotianae but no effect on the hyphal growth of P. nicotianae.