棉 花 学 报    Cotton Science     2007，19(3)：168-172

Inhibitory Mechanisms of Trichoderma harzianum TH-1 against the Pathogens of Verticillium Wilt and Fusarium Wilt of Cotton
GAO Zhi-mou¹，CAO Jun¹，PAN Yue-min¹，WU Xiang-hui²，ZHANG Zhan-hua¹
( 1. College of Plant Protection，Anhui Agricultural University，Hefei 230036，China；2. General Station of Plant Protection，Hefei 230001，China )

Abstract：The effectiveness of the present integrated control measures for the two diseases has been not satisfactory because of the shortage of ideal variety resistant to Verticillium wilt and effective chemicals for control of the two diseases. Increasing emphases，therefore，have been attached to the bio-control approach. To seek new bio-control agents，the authors had isolated and obtained Trichoderma harzianum isolate TH-1 from the soil in cotton field at Xiao county of Anhui Province. In this paper，the inhibition and mechanism of the isolatd TH-1 against the pathogens of Fusarium wilt and Verticillium wilt of cotton，Fusarium oxysporium f. sp. vasinfectum and Verticillium dahliae were further studied in vitro by applying dual culture，cup-plate test and microscopy，respectively. The results showed that in dual-culture tests，the inhibitory rates of the isolate TH-1 against the tested isolates WWKW1-1，WJKW2-4 and XXKW5-1 of F. oxysporium f. sp. vasinfectum were 54.27%，46.50% and 53.50%，respectively，and the inhibitory rate against the tested isolate HFHW-3 of V. dahliae was 37.91%. In cup-plate tests，the inhibitory rates of the isolate TH-1 against the tested isolates WWKW1-1，WJKW2-4，XXKW5-1 and HFHW-3 were 70.71%，37.80%，72.96 and 100%，respectively. It was suggested that the control effects of the isolatd TH-1 on the two pathogenic fungi were all significant when it was dual-cultured with the pathogens or when its conidium suspension was applied into the media. However，the inhibitory effect of the metabolic liquid of TH-1 on V. dahliae was not good ， and not significant on F. oxysporium f. sp. vasinfectum . It was revealed microscopically that the hyphae of TH-1 grew parallel along the hyphae of F. oxysporum f. sp . vasinfectum and V. dahliae，and formed appressorium-like structures attaching the hyphae of the pathogens. It was also observed that the hyphae of TH-1 penetrated and broke the hyphae of F. oxysporum f. sp. vasinfectum . It was suggested that TH-1 parasitized the pathogens. The results mentioned above indicated that the inhibitory effects of T. harzianum isolate TH-1 against the pathogens of Fusarium wilt and Verticillium wilt of cotton were produced most by nutrition and/or space competition and mycoparasitism. In addi，the inhibition and mechanisms of fungi in Trichoderma against the plant pathogens and their difference in different Trichoderma~ pathogen interaction systems were discussed.
Key words：Trichoderma harzianum；Verticillium dahliae；Fusarium oxysporium f. sp. vasinfectum；antagonistic mechanism  [Full Text，2986KB]