Effects Of Funneliformis Mosseae On Bacterial Community Structure In The Rhizosphere Soil Of Continuous Cropping Soybean

As an important food crop,soybean contains many beneficial nutrients,which occupy an important position in China's agriculture.At present,the increasing demand for soybeans has induced the continuous crop damage of soybeans to become increasingly prominent.Continuous cropping is the result of common effects of soil microorganisms,rhizosphere soil and crops.Continuous cropping is inhibited crop growth by soil environmental deterioration,plant autotoxicity and soil microbial community destruction,ect.In recent years,the application of arbuscular mycorrhizal fungi in relieving continuous cropping obstacles has gradually attracted the attention of scientific researchers.In this experiment,Soybean Hei Nong 48(HN48)was selected as the test material.The dominant AM fungi in the soybean field,M.sinica,were inoculated respectively for 0 year for continuous cropping,1 year for continuous cropping,3 years for continuous cropping,and 5 years for continuous cropping.And the control group was not inoculated with F.mosseae.Acid fuchsin solution dyeing method and drying method were used to measure and count soybean root mycorrhizal infection rate and soybean biomass of different continuous cropping years for 30,60,and 90 days of soybean planting,And high-throughput sequencing technology was used to determine the bacterial community structure at different time points for three consecutive years.With the increase of continuous cropping years,the biomass of soybeans will decrease.The samples in the test group inoculated with F.mosseae were significantly higher than those in the control group,which somewhat improved the continuous cropping obstacle phenomenon in soybeans.Through high-throughput sequencing,it was confirmed that the microbial diversity and species abundance at the three time points of soybean growth period generally showed a trend of decreasing with the increase of continuous cropping years,the value was the lowest in continuous cropping for 5 years.But it increased first and then decreased in the whole growth period.The sample abundance and diversity index were the highest at 60 days of soybean planting.At three time points,dominant bacteria in the rhizosphere soil were dominated by beneficial bacteria such as Gemmatimonas,Sphingomonas,Bacillus,etc,the multiple metabolic functions of the test group were also significantly better than the control group.The results showed that inoculation with F.mosseae could improve the bacterial diversity in the rhizosphere soil,increase the abundance of beneficial bacteria,and relieve the rhizosphere microbial flora that was destroyed by continuous cropping.At the same time,it was found that the inoculation of F.mosseae could increase the proportion of abundances of the genus Gemmatimonas and Sphingomonas in each sample at three time points by analyzing the abundance of the genus.Analysis of soil physicochemical properties shows that with the increase of continuous cropping years,some physicochemical properties first decreased and then increased,while the other part showed a downward trend.However,the soil physicochemical properties index increased after inoculation with F.mosseae,confirms that F.mosseae can regulate the physical and chemical environment of continuous cropping soil.The analysis of the physicochemical properties of the soil and the RDA plots of the dominant flora revealed that advantageous beneficial bacteria were positively correlated with most physicochemical factors at the early stage of soybean planting,but were negatively correlated with most physicochemical properties at 90 days of planting.Even though there are still beneficial bacteria,but with the outbreak of continuous pathogenic fungi,the bacterial niche is severely threatened,and the physicochemical properties show a negative correlation with most bacterial flora.In summary,F.mosseae has a great influence on the bacterial community structure in soybean rhizosphere soil.At the same time,it was proved that F.mosseae has a role in promoting the bacterial abundance in the rhizosphere soil,improving the metabolic function and improving the physical and chemical properties of the soil.