Changes Of Soil Microbial Community Structure Of Forage Corn And Selection Of Growth-promoting Microorganisms

The aim is to understand the impact of continuous corn cropping on the diversity of soil cultivable microbial resources,and provide information and excellent bacterial support for the in-depth understanding of the soil microbial diversity in this area and the development of microbial fertilizers suitable for the green production of corn in Gansu.In this experiment,7-year-planted corn soil was used as the research material,and nutrient-rich(NA)and selective(Ashby)media were used to separate cultivable bacteria.The obtained strains were sequenced and compared with 16 S r RNA to evaluate their production.Plant growth stimulant(IAA),phosphorus solubilization,nitrogen fixation,etc.,combined with highthroughput sequencing to analyze the soil microbial community structure of different continuous cropping years,screen out the core microbial resources that maintain soil health,and combine the obtained microbial resources to construct growth-promoting bacteria Group,evaluate its impact on the growth of forage corn,and lay the foundation for cultivating better quality corn.1.224 strains of bacteria were successfully isolated from the soil of different continuous cropping years of maize in Gansu,200 strains of different genera were identified as belonging to 56 genera,which expanded Gansu's soil microbial diversity and provided valuable bacterial species resources.Among the bacteria that can be cultivated for each continuous cropping period,the most dominant phylum is Proteobacteria,and the most dominant genus is Pseudomonas.The abundance and diversity of cultivable bacteria at the phylum level and genus level are significantly different for each continuous cropping year.As the continuous cropping years increase,the abundance and diversity of bacteria first rises and then declines and then rises in a circular manner,indicating Seven-year continuous cropping has a significant impact on the structure of soil cultivable bacterial community.2.From the bacteria isolated from the soil of different continuous cropping years of maize in Gansu,34 strains of IAA producing strains,25 strains capable of dissolving organic phosphorus,19 strains capable of dissolving inorganic phosphorus and 27 strains of nitrogen fixing were screened out.The most dominant genus is Pseudomonas Bacteria.The abundance and diversity of strains with growth-promoting functions in each continuous cropping period showed an upward trend with the increase of continuous cropping years,and there were obvious differences,indicating that 7-year continuous cropping had a significant impact on the growth-promoting functional strains in the soil.3.Through high-throughput sequencing technology,7-year continuous cropping can significantly change the soil bacterial community structure.The dominant bacteria phyla of different continuous cropping years were Proteobacteria,Actinobacteria,Bacteroidetes,Firmicutes,Acidobacteria,and Chloroflexi,accounting for 79.99 ? 82.52 % of the total community.Proteobacteria is the most dominant phyla,accounting for 34.13-47.37 %;Significant changes occurred at the genus level.With the increase of continuous cropping years,the relative abundances of Sphingomonas,Pseudomonas,and Arthrobacter increased significantly,and the dominant territories increased significantly.The relative abundances of Massilia,Devosia,and Streptomyces all decreased significantly;the 7-year continuous cropping of maize could be significantly increased Increase the abundance and diversity of bacteria;the difference in bacterial community structure between 3 continuous cropping years between 7 years of different continuous cropping is smaller than that of newly planted corn;soil p H has the greatest impact on bacterial community structure;through a cooccurrence network The analysis showed that Pseudomonas is the key genus,the genus of Sphingomonas maintaining stable soil structure.4.Through the combination of cultivable methods for bacterial isolation and growthpromoting function screening and high-throughput sequencing technology analysis,establish and construct a growth-promoting combination(PT,4 strains of bacteria)and a nodal growth-promoting combination(CT,5 strains of bacteria)),pot experiment results show that PT and CT can significantly promote the growth of corn plant height,leaf length,and fresh weight above the ground,and both can alleviate and promote the growth inhibition of corn when excessive chemical fertilizer is applied,but both have an effect on the growth of fresh weight below the ground.The effect of promoting growth is small.The growth rate of PT in plant height and leaf length is higher than that of CT,and the growth rate of aboveground fresh weight of CT is higher than that of PT.The addition of functional inoculants significantly promotes the growth of corn plants,and provides support for the subsequent preparation and application of PGPB inoculants.