| Fusarium root rot of Alfalfa, a kind of soil-brone disease, became more and more serious in the alfalfa-planting areas of Gansu, China. The Fusarium spp were obtained from the soil samples of alfalfa experiment field in campus of Gansu Agriculture University. Then the pathogenicity of Fusarium spp, enzyme activity after inoculation with different Fusarium and the pathogenicity of Fusarium isolates on different crops varieties were tested. So they can be used for biocontrol in the future.16 strong pathogenic isolates, 23 middle pathogenic isolates and 12no-pathogenic isolates were obtained. Strong pathogenic isolates were 4 strains of F.solani, 6 strains of F.oxysporium, 1 strains of F.culmorum, 1 strains of F.nivala,1 strains of F.lateritium, 1 strains of F.semitectium, 2 strains of F.trichothecioides; 23 middle pathogenic isolates were 8 strains of F.soalni, 3 strains of F.oxysporium, 8 strains of F.lateritium, 1 strains of F.equiseti, 1 strains of F.tricinctium, 1 strains of F.udum, 1 strains of F.semitectium; 12 no-pathogenic isolates were 4 strains of F.solani, 4 strains of F.oxysporium, 2 strains of F.equiseti, 1 strains of F.lateritium, 1 strains of F.culmorum, 1 strains of F.moniliforme.The activities of enzyme were different after inoculated with different Fusarium spp ; The results showed that variations of enzyme activities of POD,PPO,PAL,CAT and SOD were closely related to the pathogenicity of Fusarium spp after inoculation; The maximum value of CAT content was appeared after 6d inoculation, the maximum value of SOD, POD,PPO,PAL content was appeared after 9d inoculation. Moreover, the strong pathogenic strains value of enzyme content after inoculated were much higher than that of no-pathogenic strains.The 12 no-pathogenic isolates on Derby showed a little different pathogenicity on other 6 crops. a little part showed strong pathogenicity or middle pathogenicity.But most of them were the weak or no-pathogenicity. |
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