Selection Of Dominant Bacteria In In Situ Nitrogen Metabolism And The Effect Of Compound Bacteria On Nitrogen Transformation In Tobacco-planting Soil

In order to solve the low mineralization rate of soil organic nitrogen in the prophase of fluecured tobacco,that can not satisfy the nitrogen absorption of flue-cured tobacco,screening of nitrogen metabolism dominant microorganisms made of compound bacteria from the Qianxi tobacco-planting soil.Exploring the effect of in situ application in Qianxi,an,and ectopic applicantion in Weining.The specific results are as follows:1.The three major microbial groups in tobacco-planting soil were studied by dilution plate method in six tobacco-planting soils which used local conventional fertilization in Qianxi and Weining.The results show that: the main microbial compositions of soil in two regions of are similar,they are bacteria,actinomycetes and fungi.The percentage of bacteria is 68.14%-87.48% in the total amount of soil microorganisms.The minimum percentage of fungi in the total number of soil microorganisms is 3.67%-12.12%.The percentage of actinomycetes which are less sensitive to the environment is 8.76%-26.19%.In every period of flue-cured tobacco growth,the soil bacterial community in Qianxi was relatively stable,the change amplitude was relatively small,and the variation range of soil bacteria in Weining area was relatively large.The changes of soil actinomycetes in two regions were relatively large during the whole growth period.the number of soil bacteria in the Qianxi and Weining regions began to grow after flue-cured tobacco transplant,and both peaked in the cluster and then began to decrease,but in the bud,the soil bacteria in the Weining area began to increase,while the soil bacteria in the Qianxi area declined.In general,the number of soil microorganisms in both places is the maximum in the cluster period.2.Using ammonifying bacteria,nitrosation bacteria isolation medium isolated advantage bacterium group from the tobacco-planting soil in different ecological conditions in Bijie.Then using nitrification bacteria,and screening with color method and action intensity to obtain the 7 strains with high nitrogen conversion intensity.By 16S-DNA-PCR Physiological and biochemical identification,ultimately determine the application in the preparation of compound microbial agents strain number respectively1,2,3,4,5,6,7,a total of seven.By using the method of filter paper,the antagonistic test was carried out between the strains of the compound microbial solution,and there was no antagonism;between the strains of the7 strains,which could grow together and not affect each other,and could be used in the preparation of the compound microbial agent.3.Application field test method to study the effect of nitrogen conversion compound functional bacteria,through the analysis of flue-cured tobacco planting soil and the high throughput sequencing of soil bacteria in the growth stage,The results showed that adding microbial agents in two places was helpful to improve the microbial activity of tobacco-planting soil,the urease content and soil bacteria and bacteria number,the mineralization of organic nitrogen,the bacterial community structure,the beneficial microorganisms(such as the sheath of Aeromonas,Streptomyces,Aeromonas,anaerobic bacteria,etc.)and nitrogen transformation of dominant bacteria(such as Bacillus,nitrite,nitrifying bacteria)abundance.Thus accelerating the decomposition of organic nitrogen in the mature soil of flue-cured tobacco,it is advantageous to the increase of inorganic nitrogen in the long term of flue-cured tobacco,so that the nitrogen and organic matter content in flue-cured tobacco is kept low,and the microbial agent can improve the yield and the chemical quality of the tobacco.There are some differences in the application effect of the compound microbial agent in the two places.In the field of soil organic nitrogen transformation,the alkali solution nitrogen in the soil after Qianxi application,the increase of ammonium nitrogen and total nitrogen in the long term was better than that of Weining,and the decrease of the amount of bacteria and nitrogen-transforming bacteria in soil biological activity was better than that of Weining,But the improvement of soil urease content is inferior to Weining.It takes a certain period of time to recover and adapt to the microbial agent.In order to accelerate the decomposition of organic matter in the long term,it is effective to apply the bacteria in the rooting stage and in the Weining stage,and the effect is best when the Qianxi is applied to the root stage.The addition of compound bacteria was 10 billion/strains.In Qianxi,due to the microbial agent in situ application of microbial agents can be better colonization,and the stability of the local soil microbial flora has little effect,so it shows a better effect than Weining application.