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Fusarium wilt of watermelon caused by Fusarium oxysporum f.sp.niveum is world wide in occurrence,which belongs to Fungal soil-borne diseases.Spore germination,mycelial growth and sporulation are important stages of disease spread,the medicament which can block any growth stage of pathogenic bacteria can control the disease.The effect of microchemical substances in anaerobic fermented liquid from rice straw and cyanobacteria(1 ∶ 1)on Fusaruim oxysporum f.sp.niveum growth was investigated.It included spore germination,spore number,and mycelial growth.The results showed that spore germination number reduced 6.25%、37.5%、77.5% respectively at the 5%,10% and 20% concentration groups,especially inhibited by 100% at 40% concentration of biogas slurry.The spore production could be inhibited by 98.74% at 20% concentration of biogas slurry.The aerial mycelial growth could be almost inhibited at 100% concentration of biogas slurry.Further analysis by gas chromatograph-mass spectrometer found that there are many kinds of alkyl substances in the organic component from biogas liquid.Three microchemical substances,CCl4,C2Cl6,CH3CH(OCH2CH3)2 measured in biogas liquid by GC-MS analysis had distinct inhibition effects.The inhibition effects increased with their concentrations,especially CH3CH(OCH2CH3)2.The spore germination number reduced 20.22%、28.84%、40.82% respectively when CCl4,C2Cl6 and CH3CH(OCH2CH3)2 were added in culture medium at the 0.1% concentration;and the inhibition rate respectively increased to 81.27%、79.78%、86.52% at 0.5% concentration.The spore germination were inhibited by 100% at the 0.75% concentration of three chemicals;The numbers of producing-spore reduced 5.67%、18.05%、8.72% respectively at the 1% concentration of three chemicals;The inhibition rate was 80.91%,75.59% and 99.22% respectively at 3% concentration of three chemicals.The restraint effects of three chemicals were very notable on the aerial mycelial growth with training four days,especially CH3CH(OCH2CH3)2 at 0.10%—1.00% concentration and CCl4 or C2Cl6 at the concentration more than 0.25%.The inhibiting rate would get to 90.4% when three chemicals at 1.00% concentration were added in the medium.The tolerance of Fusarium oxysporum f.sp.niveum on three microchemical substances increased with prolonging culture time.The aerial mycelium in every tested group grown at some extent.The restraint rate of three chemicals was 77.96% on the aerial mycelial growth with training seven days,especially 1,1-CH3CH(OCH2CH3)2 getting to 87.22%.The restraint effects increased with the concentration in the range of 0.10% to 1.00%.But the inhibiting rate declined slightly comparing with four days at same period.The experiment results showed that three chemicals remarkably restrained the growth of prophase aerial mycelial.Multi-specific ingredients were included in the biogas liquid to inhibit the pathogenic microbe.Biogas slurry can be used to control the growth of pathogenic microbes as one of the preferred agents,which will resolve the long-troubled problem about the disease and provide reference to prevent fusarium wilt of watermelon for the future study. |
