| There are two problems in the process of Rehmannia glutifnosa production are still difficult to solve,First it can not continuous cropping, the soil need interval planted8to10years,otherwise severe growthretardation occurseven dead. Another is Septoria digitalis Pass and Fusarium solani. Recent studies havefound that some of endophyte in the soil has a certain activity which is useful to the decomposition oforganic molecules and the antagonism of other pathogenic microorganisms.So we isolated Endophyticbacteria with antimicrobial biocontrol activity from Rehmannia glutifnosa,to make microbial inoculum addin the pots and field.Then applied microbial inoculum to Rehmannia rhizosphere soil, detecting the impactof activity endophytes agents on Rehmannia rhizosphere soil enzyme activities and chemical properties atdifferent growth stages. Monitoring the dynamic changes in their microbial flora and exploring the impactof endophytic bacteria as probiotics for the prevention of plant diseases soil enzyme activity, the chemicalproperties and the rule of rhizosphere soil microbial communities evolve. Specific findings include thefollowing aspects:(1) Endophytic bacteria of Rehmannia glutifnosa were isolated by using the method of agar plates.Their antagonistic activities were tested on agar plates by using Escherichia coli, Staphalocolcus aureus,Aspergillus niger, Septoria digitalis Pass and Fusarium solani. Thirty two endophytic bacteria wereisolated from Rehmannia glutifnosa, in which30strains had different extent of antagonistic activities onone or more species of the tested microbes,8strains showed strong and wide antagonistic activities to E.coli, St. aureus and A. niger, and2strains had high resistance to all the tested microorganisms, especially tothe two plant pathogenic microorganisms. The32endophytic bacterial isolates were distributed in threegenera, Bacillus, Pseudomonas and Escherichia, while the isolates that had resistance to S. digitalisPass and F. silani were mainly grouped in Bacillus.(2) The active endophytic bacteria of Rehmannia glutifnosa have a certain improvement of theprevention and cure of plant diseases. Potted results showed, the disease incidence rate of potted seedlingsapplying germs was100%. While applying germs and microbial inoculants a had a obvious bio-controleffect on the resistance to root rot and Septoria lycopersici, the control efficacy reached33%and44%respectively. Field tests showed that the continuous cropping soil that applied microbial inoculants as control the incidence rate reached68%.After microbial inoculants1processing the disease incidence ratewas20%, reduced by48%than control. And after microbial inoculants2processing the disease incidencerate was24%, reduced by44%than control. And situation of the disease plants after the microbialinoculants treatment was not serious, mainly concentrated in level1, while the control had reached to level5.(3) Field test results showed that, the plant,chemical properties and enzyme activity are changed indifferent growth periods.From the Q-PCR results, cropped soil compare control, total number of bacteriabecome less, total number of fungus become more. The total number of bacteria is far from funqus.Thenumber of bacteria in cropped soil1year harvesting stage was4.74×1014copies/g slightly lower thanthe cropped soil2year harvesting stage4.91×1014copies/g, The number of funqus in cropped soil1yearharvesting stage was1.54×103copies/g was significantly higher than cropped soil2year harvesting stage9.78×102copies/g. the number of bacteria and fungi of cropped soil1year swelling stage both more thancropped soil2year swelling stage.MISeq high-throughput analysis result shows that, the advantage of rhizosphere bacteria proportionhas certain change, in which change is larger at the time of harvest actinomycetes ratio reduce rapidly,cropped soil1year reduced to5.12%from23.38%, continuous cropping soil reduced to7.05%from18.10%. There was no significant difference from the advantage of rhizosphere bacteria in cropped soil1year compare with cropped soil2years. The advantage fungi in the rhizosphere system are mainlydistributed in Unclassified、Guehomyces、Alternaria、Ascomycota_norank、Fungi_norank.Alternariaproportion reduced quickly in cropped soil1year, before planting was20.95%, the swelling stage reducedto2.54%, the harvestry stage was1.81%. Thielavia proportion also falling rapidly. In the cropped soil2year stage,unclassified bacteria increase rapidly, Guehomyces reduced, Thielavia is almost disappeared,Ascomycetes and Ascomycota_norank rates also increased significantly. the proportion of Gibberellagradually reduce disappeared in the cropped soil2year harvestry stage.(4)Endophytic bacteria as probiotics has a important role in overcoming continuous cropping obstacle of Rehmannia glutinosa: Two groups of microbial inoculants had a great improvement on the growth condition of continuous cropping soil of huai rehmannia. In bulking stage, the effect of microbial inoculants treatment group was very obvious. Variance analysis showed that, the seedling stage, bacteria agent2 treatment groups of leaf length, leaf width, salience than bacteria strains agent1, bacterium agent1issignificantly higher than control. In disk stage, bacterium agent treatment group compared with controls,the width of blade reached significant level. Leaf blade length and plant height also slightly increased. Inbulking effect is most obvious, two groups of bacteria agent of leaf length, leaf width, plant height weresignificantly higher than control. As a result, the bacteria agent treatment on continuous cropping soil huairehmannia root growth conditions have greatly improved.Microbial agents on soil chemical properties have certain improvement: The soil treated with pHagent2is significantly higher than control at seedling stage, plate of tree stage and swelling stage,reachedthe significant level, The pH of the continuous cropping soil after bacteria agent2processing was7.06inthe plate of tree stage. The groups of applying bacteria agent2, the Soil organic matter content wassignificantly higher. While there were no significant effect on soil total nitrogen and total phosphoruscontent. Microbial inoculants had a significant effect on the enzyme activity of continuous cropping soil.Urease and invertase activity had improved that applying two groups of microbial inoculants, then had nosignificant effect on soil catalase activity. |
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