Studies On Biocontrol Of Rehmanniae Fusarium Wilt

1.For the 22 isolates of fungi, 58 isolates of bacteria and 128 isolates of isolates of actinomycetes which were obtained from the rhizosphere of Rehminnae plants, the dual cultures were tested in vitro. The result showed that 13 strains of fungi, 4 strains of bacteria and 65 strains of actinomycetes have antagonism, but a several of them had probiosis effects more or less instead of inhibition effects. Among them, we sifted 9 strains include(B6, B21, T4, T3, S15, S72, S92, S95, S52)which have better inhibition effects to pathogen.2. We did pot and plots experiments to the microbes that have better antagonistic effects. The results showed that the control effects of 5 strains (S15, S72, S52, B6 and T4) were over 50.00%. In pot, the result showed that S15 and S72 have best control effects, the number is 67.80% and 62.00%, the second is S52, B6 and T4, the control effects are above 50.00%. The control effects of 9 strains were studied in plots. The results is that S15 have best control effects, the number is 76.60%, and S72, B6 were the second with effect all above 65.00%. Futhermore, we did the growth-promoting test in pot, and 3 strains (S52, S15 and S95) showed a growth-promoting and yield increasing effect on Rehminnae.3.Biocontrol mechanism of inhibition and imicroecology were studied in this experiment. The result showed that the inhibition effects of 2 strains (S72 and B21)to conidial germination are all above 80.00%. The growth of hyphae were inhibited by T4, S72, B21 and B6, the number are all over 50.00%; among them, the effect of T4 is 61.90%. In vitrol, the growth speed of T4 is apparenlly faster than pathogen. Therefore the presumptive antagonism modes of T4 were antioiosis, and comtition for space and nutrition against the pathogen, but the mechanism of S15, S72 and S52 is antioiosis, and they can produce some kind of inhibitive substance...