Experimental Study On Inhibition Of Leaf Spot Pathogen Of Taxus Yunnanensis By Biogas Slurry

At present, Alternaria alternata occurred seriously and has seriously affected the growth, medicinal and ornamental values.Many studies showed thatbiogas slurry had good inhibitory effect for most plants pathogenic bacteria.This study mainly aimed to obtain biogas slurry inhibiting efficiently Alternaria alternata through the above study and could also eventually provide theoretical guidance for the actual agricultural productionin the pest control.The different biogas slurry of normal fermentation were used to do inhibition experiments on Alternaria alternata.We could evaluate the antimicrobial effect of biogas slurry through the observation of pathogenic bacteria growth 4d. This paper obtained research results as follows:1. The antimicrobial activities of biogas slurry of 12 kinds of raw materials display that biogas slurry of artemisia annua, cantaloupe and tobacco stem were better and inhibitory rate were respectively75.8%, 74.2%, 71.5%. The findings ofwater hyacinth residue and lees dynamic inhibition were similar. The antibacterial effect of biogas slurry was closely relatedtothe strength of fermentation time and itwas first increased and then decreasedalong with the fermentation time.The two raw materials wererespectively fermented to the 28 th and 35 th day of biogas slurry to have the best antibacterial effect.2. Biogas fermentation process had an impact on the antibacterial effect of biogas slurry.Experimentalresults showed that the optimum processparameters:the antibacterial efficiency of biogas slurryenriching inoculum by vetiver and pig manure were respectively 54.65%,48.28%.The antibacterial effectof biogas slurry from fermentation inoculumof10%,15%,20%,30% were different. The greater the inoculation concentration, the better antibacterial effect. Best antibacterial effect of is biogas slurry of inoculum concentration 30% and inhibitory rate was 69.6%, while the inhibitory rate of 10% was 55.8%.The biogas slurry from fermentationunder the normal temperature, medium temperature, high temperature had small differences about antibacterial effect and the inhibition rate were respectively 66.08%, 64.13%,68.55%. The biogas slurry from fermentationliquid concentration of 6%, 8%, 10%,12% were differentabout antibacterial effect and inhibition rate of 8% was the best to reach 60.6%. The biogas slurry from fermentationliquid ofinitial pH 6.0,6.5,7.0,8.0about antibacterial effect are different and antibacterial activity of pH = 6.5 and pH =8.0 is stronger, and the inhibitory rate was respectively 60.57%, 57.52%.Theantibacterial activity of pH = 7.0 was weakest and inhibitory rate was only29.44%.The inhibitory effect of biogas slurry from fermentationliquid adding Tween-20 and cellulase fermentation was stronger than that of the control group,while adding the glucoamylase were significantly weaker than that of the control group.3. Study on the physical and chemical factors affecting antibacterial effect of biogas slurry showed that the bacteriostatic effect was proportional to the concentration and inhibition rate of biogas slurry10% was only 33.84%, and the original slurry antibacterial rate was as high as 75.8%. The inhibitory effect was closely related to pH of artemisia biogas slurry. It was found that the antibacterial effect was relatively weak under the condition of strong acid, but it was relatively strong under strong alkaline conditions.In addition, the antibacterial effect of ethyl acetate extraction independents with pH.Consequently, it indicates that pH of biogas slurry mainly influenced the microorganisms in the biogas slurry to affect antibacterial effect. It could enhance the antibacteria effect from different degree to add humic acid,gibberellin, VB₁ and VB₂ in theartemisia biogas slurry. Their optimal concentration was 3%, 0.4%, 0.1%, 0.4%, 1%, but VB₆ weaken its antibacterial effect. In addition,the inhibition effect of biogas slurry along with the increase of treatment temperature was gradually weakened, and its inhibitory rate was almost zero, especially after high temperature sterilization.4. The antimicrobialresearches of biogas slurry extraction showed that its antibacterial effect was different for extraction of the same kind of biogas slurry of organic solvents with different polarities. Extraction of ethyl acetate and chloroform had the most antibacterial effect,but the bacteriostatic compositions of different biogas slurry was similar.Besides, the antibacterial effect was weaker after biogas slurry of eupatorium adenophorum spreng was extracted than that of its own extraction.However, it becomed stronger after two extraction were mixed. The castor stalk was similar. This indicated that the two plants contained ingredients of strong antibacterial activity, but it was degraded in biogas fermentation process. The antibacterial effect could be enhanced if the antibacterial active ingredients and biogas slurry were mixed.5. The comparative study on antibacterial effect of biogas slurry and conventional pesticides showed that the antibacterial effect of artemisia biogas slurry was generally higher than the vast majority of conventional pesticides apart fromthiophonate-methyl. Artemisia biogas slurry with three pesticides were respectively mixed according to different mixing ratios to show certain inhibition effect for Alternaria alternate and the inhibitory effect was more significant along with the prolonging of pathogen incubation time. The antibacterial effect of the mixed liquid according to the same proportion was different due to different kinds of pesticides.6. The antibacterial effect of biogas slurry on Alternaria alternata was mainly closely related to internal complex microorganism of biogas slurry,including to antagonism,competition for nutrients or the formation of anaerobic micropoint ring,but the active substance of biogas slurry had little effect on the antibacterial effect.