| Although the fertilizer can improve crop yield in a certain extent,it will lead to some serious consequences under long-term and unreasonable application,such as the destruction of soil structure,soil degradation and soil fertility decline.In particular,the pollution of the chemical fertilizer to the environment has been in urgent need of control.Compared with chemical fertilizer,microbial fertilizer has the advantages of environment-friendly,resource saving,green safety and so on.Therefore,the research and popularization of microbial fertilizer is in line with the needs of the current social sustainable development.Based on this,Multifunction microbial fertilizers applied to bananas were studied in this study.The pathogenic fungi of Banana Fusarium wilt were used as the target microorganism to isolate and screen the antagonist.The bacteriostatic activity and bacteriostasis mechanism of the antagonist were studied.A stable microbial community was constructed by combining with other functional bacteria,and the stability of the community during the period of culture was analyzed.The optimal interval of culture conditions was determined by single factor experiment,and the optimal fermentation conditions were obtained by the uniform design experiment to improve fertilizer efficiency.A pot experiment was carried out to determine the effect of functional microbial community on the prevention and growth of banana seedlings.By high-throughput sequencing,the diversity and structure of soil microbial community affected by functional microbes were analyzed.understand the effect of microbial manure on Soil Micro ecology.The main achievements of this study are as follows:(1)The soil from the banana garden and fermented food are used as the separation test materials for the antagonistic bacteria.131 strains of bacteria were obtained.52 strains of antagonistic bacteria were screened out with the pathogen of Banana Fusarium wilt as the target bacteria.Strain 4-z-3 was used as the representative.It was found that it had good antagonistic effect on eight plant pathogens.After the morphological characteristics,physiological and biochemical tests and 16S rDNA gene sequence alignment,it was identified as B.siamensis.The bacteriostatic active substances of antagonistic bacteria were extracted by ammonium sulfate precipitation.The damage of bacteriostatic substances to the morphological structure of pathogenic bacteria was analyzed by scanning electron microscope and projecting electron microscope.The content of N-acetyl glucosamine in the pathogens treated with different concentrations of antagonists was measured.It was found that the antagonist could decompose the cell wall of the pathogen.(2)Select the functional bacteria stored in the laboratory,the strain number is 6N2-5,bao-5-6,M3-4.Antagonistic symbiotic experiments were carried out between the various functional bacteria and the isolated antagonists.It is determined that all the functional bacteria can be symbiotic and can be co-cultured.The antimicrobial resistance of each functional bacteria was tested and then domesticated.The type and concentration of the labeled antibiotics are:Strain 3-Z-8B is 200 ?g/ml chloramphenicol,strain 4-z-3 is 400?g/ml tetracycline,strain 7-z-20 is 300 ?g/ml streptomycin,strain Bao-5-6 is 50?g/ml gentamycin,strain 6N2-5 is 150 ?g/ml rifampicin,strain M3-4 is 350 ?g/ml ampicillin.The labelled strain was fermented for 5 days.It was found that all strains were able to grow normally,propagate rapidly at 3-4 days,and the number of each strain was the highest at fourth days.The constructed microbial community is a stable community.(3)The single factor experiment was carried out with five factors:carbon and nitrogen ratio,inoculation amount,initial pH value,rotation speed and culture time.Then the best interval of each factor was determined:the best initial pH was 6?7.5,the best C/N ratio was 6:1?21:1,the optimum speed was 140 r/min?200 r/min,the best inoculum size was 4%?10%,and the best culture time interval was 2 days?5 days.The uniform experiment scheme was designed according to the results of single factor experiment.The optimum conditions for culture conditions are as follows:the time was 110 h,the initial pH value was 5.8,the speed was 146 r/min,the inoculation amount was 9.9%,and the carbon and nitrogen ratio was 6.4:1.The indicators at this time are as follows:the rate of bacteriostasis was 56.97%,the amount of phosphorus was 18.33 mg/L,the amount of potassium solution was 249.41 mg/L,and the nitrogen fixation amount was 620.82 mg/L.The indicators of optimized conditions of fermented bacterial manure were almost significantly higher than that before optimization,in addition to the potassium solubilizing quantity had no significant difference.(4)Different treatment groups were set up for pot experiment according to the different substances added.Two months later,the incidence of each treatment infected by pathogenic fungi was measured.The best prevention effect was F treatment,the disease index was only 21.4,the prevention and control effect of Fusarium wilt reached 74.1%,which effectively inhibited the occurrence of Banana Fusarium wilt.Only 50%bacterial manure added to the treatment H,the control effect is reduced to 41.3%,down 32.8%,it proves that the antibacterial effect of bacterial manure.(5)By comparing the chlorophyll,plant height,biomass,leaf and plant height of banana seedlings,it is found that the growth promoting effect of treatment G can be best,followed by D,E added microbial fertilizer had significant growth promoting effect.By comparing the indicators of soil physical and chemical properties such as total nitrogen,available potassium,available phosphorus and organic matter,we can find that the results of all treatments are basically the same as those of the growth promoting experiment.From the big to the small,they still treatment G,treatment D and treatment E.The promating effects of each treatment were demonstrated.Different treatments provide different nutrient elements,so the effect of growth promotion is different.(6)The potted soil was collected for high flux sequencing.After that,OTU analysis showed that the top five of the proportion of soil microbial community was Proteobacteria,Actinobacteria,Chloroflexi,Acidobacteria and Bacteroidetes.There were significant differences in the microbial community between seeding soil CK and each treatment.Moreover,microbial diversity is also low,because the growth of plants is beneficial to the improvement of microbial diversity and the stabilization of microbial communities.Compound fertilizer has the greatest influence on soil microbial community.Therefore,the treatment which was added compound fertilizer is different from other treatments.Moreover,adding compound fertilizer will reduce microbial diversity.The influence of Fusarium oxysporum on soil microbial community was second,and the diversity of microorganisms treated by pathogen was significantly reduced compared with the corresponding treatments,and the proportion of bacteria in multiple phylums was different from other treatments.Effect of microbial fertilizer on community is weak than compound fertilizer and pathogenic fungi.It helps to improve community microbial diversity,and it can effectively stabilize microbial communities and reduce the effects of pathogens and compound fertilizers on soil microbial communities.In addition,the effect of time factors on microbial community in the treatment of compound fertilizer was obvious,and the difference was significant.Some bacteria are sensitive to the environment and can react quickly when the environment changes.The results showed that the most sensitive bacteria to the environment were Nitrosomonas and norank P Saccharibacteria,followed by Xanthomonas and Xanthomonas. |
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