Effects Of Cellulose Degrading Bacterium Bacillus Sp. CGMCC 19895 On Wheat Growth And Soil Microbial Community

Straw returning to the field is helpful to the utilization of agricultural waste resources,which is an important measure carried out by the state.In order to improve the decomposition efficiency of straw,previous researchers have screened a large number of functional strains and systematically analyzed the promotion effect of these strains on straw degradation after application.However,farmland is a complex ecosystem.When using these strains,we should not only pay attention to their effect of straw degradation,but also consider their impact on crop growth and indigenous microorganisms in farmland.Bacillus sp.CGMCC19895 is a patented strain with high cellulose degrading performance and biocontrol.In this study,the strain CGMCC19895 was used as the test material.Through greenhouse tests and field tests,the effects of the strain on straw returning to field decomposition,wheat growth and yield,and soil microbial community were analyzed under the conditions of single and combined application with other functional strains,and the field application effect of the strain CGMCC19895 was comprehensively evaluated.The results are as follows:(1)In the greenhouse experiment,cellulose degrading bacterium Bacillus sp.CGMCC19895 had a strong ability to promote the growth of wheat and increased the aboveground dry weight of wheat from 0.390 g to 0.587 g.When combined with Alcaligenes sp.CGMCC 21555,the growth promoting effect of the strain decreased without straw addition,which was 17.3% lower than that of Alcaligenes sp.CGMCC 21555 alone,and the growth promoting effect increased after straw addition.It had the same effect as single application of Alcaligenes sp.CGMCC 21555.The results showed that the addition of straw was beneficial to the colonization of cellulose degrading bacterium Bacillus sp.CGMCC19895 and Alcaligenes sp.CGMCC 21555.The colonization status of Alcaligenes sp.CGMCC 21555 was doubled.The enhancement of this colonization ability may have important influence on the growth promotion effect of the strain.(2)In the straw returning test,the degradation rate of straw in surface soil(0-20 cm)and middle soil(20-40 cm)could be improved by applying cellulose degrading bacteria CGMCC 19895.When the cellulose degrading bacteria CGMCC 19895 was mixed with cellulose degrading bacteria CGMCC 25756,the degradation effect decreased with the increase of soil depth.It is speculated that the physical and chemical conditions of deep soil are not conducive to microbial growth,resulting in slow degradation of straw.Further analysis showed that both single and mixed bacteria could significantly affect bacterial diversity and community structure,and mixed bacteria treatment had significant effects on microbial composition in middle soil(30 cm)and deep soil(50 cm),mainly manifested as an increase in the abundance of actinomycetes and a decrease in the abundance of Acidobacteria.(3)In the field wheat planting experiment,the mixture of cellulose degrading bacteria CGMCC 19895 and cellulose degrading bacteria CGMCC 25756 increased the wheat yield when straw was returned to the field.Further study showed that the mixed use of strains affected soil microbial community structure and soil physical and chemical properties,and soil phosphorus content had a strong correlation with the increase of wheat yield.In addition,straw returning combined with cellulose degrading bacteria can improve the complexity and stability of wheat rhizosphere microbial community,which may contribute to the increase of wheat yield.In this study,the practical application effect of cellulose-degrading bacteria screened in the preliminary work of the laboratory was verified through straw turning back to the field test and wheat planting combined with inoculant test.In addition,the influence of multi-strain mixed application on the function of inoculant was preliminarily discussed from the perspective of microbial interaction and colonization,which provided support for further optimization of the application technology of inoculant and improvement of its effect.