Elevated CO₂ Concentration On Soil Enzyme Activities And Microbial Community Characteristics In The Root Zone Of Lycium Barbarum L.

Soil is a key component of the terrestrial ecosystem,and it plays an irreplaceable role in the response and adaptation mechanism of global warming.In this paper,in order to explore the dynamic changes of the soil microenvironment at the roots of crops under the influence of global climate warming,Open-top chamber simulation experiment of CO2 concentration increase control was conducted in Yongning Counity,Yinchuan City,Ningxia,and selected ’Ningqi No.1’cutting seedling was used as the material,and the natural environment CO2 concentration was used as the control(CK,400±20 μmol·mol-1),and the atmospheric CO2 concentration(TR1,600±20 μmol·mol-1)was increased by 0.5 times.1.0 times the atmospheric CO2 concentration(TR2,800±20 μmol·mol-1)was used to determine soil microbial biomass carbon and nitrogen and soil enzyme activities in the root zone of Lycium barbarum.The plate method,Biolog-ECO method and high-throughput sequencing technology were used to compare The combined method comprehensively analyzes the soil microbial community diversity and community composition in the root zone of wolfberry to determine the dynamic characteristics of the soil microenvironment at the root of wolfberry under elevated CO2 concentration.Metagenomic analysis reveals the function of the soil microbial community and the response of metabolic pathways to elevated CO2 concentrations.The results of this study can provide a theoretical basis and new ideas for the formulation of soil management systems for medlar plantations in Ningxia,and provide a scientific basis for the formulation of measures for agricultural production to respond to climate change.The specific research results are as follows:1.The increase of atmospheric CO2 concentration increased the activities of catalase,urease and invertase in the root zone of wolfberry by 56.98%,20.97%,and 45.05%,respectively,while polyphenol oxidase decreased by 24.97%;soil microbial biomass Both carbon and nitrogen increased by 14.50%and 23.61%respectively.2.The total number of soil microorganisms in the whole growth period of Lycium barbarum showed an upward trend and then a downward trend.Compared with the control,the treatment wife elevated atmospheric CO2 concentration reduced the number of fungi and increased the number of bacteria and actinomycetes.Among them,the total number of microorganisms was the largest when treated for 90 days.There are differences in the metabolic capacity of soil microorganisms between different CO2 concentration treatments.The general trend of changes in the metabolic activity of soil microbial communities is:atmospheric CO2 concentration in natural environment<0.5 times increase in atmospheric CO2 concentration<1.0 times increase in atmospheric CO2 concentration.3.The soil microbial community in the root zone of Lycium barbarum has a higher utilization rate of amino acids,esters and amine carbon sources,while the utilization rate of sugars and acids is lower.Utilization intensity of L-asparagine,D-mannitol,L-serine,L-asparagine,ethylamine,4-hydroxybenzoic acid and Tween 40 by soil microbial communities under different elevated CO2 concentration treatments However,the utilization and metabolism of y-hydroxybutyric acid by the soil microbial community under the treatment of atmospheric CO2 concentration in natural environment is significantly higher than the treatment with elevated CO2 concentration.4.Under the treatment of elevated atmospheric CO2 concentration,10 phyla,30 classes,67 orders,144 families,256 genera,and 370 species of fungi were detected in the soil of the root zone of Ningxia wolfberry.In the phylum classification level,Ascomycoa is the main phylum.Among them,the concentration of atmospheric CO2 increased,the abundance of Gibberella in the root zone of Ningxia wolfberry decreased,and the abundance of Fusarium increased.A total of 38 phyla,121 classes,288 orders,453 families,808 genera,and 1588 species of bacteria were detected.The dominant groups of soil bacteria with different atmospheric CO2 concentrations are Actinobacteria and Proteobacteria and Acidobacteriota accounted for 24.58%,20.91%and 18.19%respectively.In the class classification level,Alphaproteobacteria and Vicinamibacteria are the main ones.Under the genus classification level,the dominant genus of each CO2 concentration treatment is different.The abundance of most bacterial genus in the soil of Lycium barbarum root zone increases with the increase of CO2 concentration,and the most obvious are the genus Vicinamibacterales and Vicinamibacteraceae.5.Catalase and invertase in the soil of the root zone of wolfberry are significantly positively correlated with microbial biomass carbon and nitrogen,and soil polyphenol oxidase is significantly positively correlated with microbial biomass carbon,but not significantly correlated with microbial biomass nitrogen;urease The activity has the greatest influence on the number of soil fungi in the root zone of Lycium barbarum.Catalase has the greatest influence on bacteria and actinomycetes,followed by urease.Therefore,the activities of catalase and urease are important indicators to determine the soil microbial biomass in the root zone of wolfberry.