Effect Of Soil Moisture On Microbial Diversity In The Rhizosphere Of C.Oleifera

Camellia oleifera is one of the important edible oil species in China,and it plays an important role in China's grain and oil safety strategy,targeted poverty alleviation and rural revitalization.Camellia oleifera is mainly distributed in the red soil area of southern China.Seasonal drought is one of the important reasons for restricting the increase of Camellia oleifera production.Rhizosphere soil microorganisms are an important part of rhizosphere microecology.They play an important role in the process of rhizosphere soil nutrient transformation and plant growth and development,and are very sensitive to moisture.In this paper,the main cultivated Camellia oleifera variety 'Huajin' in the hilly region of Camellia oleifera red soil was used as the research material to determine the variation law of the rhizosphere microbial diversity of Camellia oleifera under natural drought conditions.Changes in rhizospheric soil nutrient status,microbial biomass,microbial species richness,and community structure diversity are designed to provide theoretical guidance for soil moisture management in Camellia oleifera forests.The main results are as follows:(1)Under natural drought conditions,the water content in the rhizosphere continued to decrease,and the daily change in the flow rate of Camellia oleifera tree showed a "several" trend,and the monthly change showed a trend of first increasing and then decreasing;the change in water content significantly affected Soil pH,ammonium nitrogen(NH4+-N)and nitrate nitrogen(NO3--N),correlation analysis shows that soil moisture content(SM)is significantly negatively correlated with available nitrogen(AN),and extremely negatively correlated with NH 4+-N and NO3--N;high-throughput sequencing results show that each group under natural drought There is no significant difference in the richness and diversity of the bacterial communities in the rhizosphere soil.Chloroflexi,Actinobacteria,Proteobacteri,Plantomycetes and Acidobacteria are abundant.The most prevalent category,the two dominant classes of fungi are the Eurotiomycete and Sordariomycetes.In the LEfSe analysis,41 different bacterial strains and 113 fungi strains were found between the treatments.Co-occurrence network analysis found that Bacteroidetes,Firmicutes and Dependentiae in soil bacteria were significantly positively correlated with SM,and fungi Eudicyledonae and Microbotryomycetes were significantly positively correlated with SM.(2)The pot experiment showed that when the absolute water content of the soil decreased to a low level(5%-15%),it would cause the photosynthetic capacity of Camellia oleifera leaves to weaken,the plant growth slowed down,and the ability to obtain nutrients weakened,which was different after the soil was rehydrated.The degree of recovery indicates that the plant growth compensation is its compensation method after drought and rewatering.The measurement of rhizosphere soil showed that there were significant positive correlations between SM and pH and available potassium in rhizosphere soil under different treatments,and extremely significant negative correlations with total nitrogen(TN),NO3-N,available phosphorus(AP)and TK;each treatment after rewatering treatment total phosphorus(TP),total potassium(TK)and available nutrients have decreased,and pH has increased.High-throughput sequencing showed that W4(20%-25%volumetric water content)had the highest shannon index,chao index and ace index.Rehydration could improve the rhizosphere environment of Camellia oleifera and increase the richness and diversity of microbial communities.The dominant species of rhizobacteria and fungi are basically the same as field experiments.Rehydration reduces the relative abundance of bacteria Acidobacteria,Thermoleophilia,and increases the relative abundance of Ktedonobacteria,Saccharimonadia and Bacilli.(3)Redundancy analysis showed that physical and chemical factors such as SM,NO3--N and TP in the rhizosphere soil of Camellia oleifera had significant effects on the microbial community structure.In comprehensive field and pot experiments,the bacterial categories that have significant effects on soil water content are Patescibacteria,Cyanobacteria,Bacteroidetes,and fungal populations include Orbiliomycetes,Leotioycetes,Chlorophyceae,Rhizophydiomycetes and Eurotiomycetes.From the perspective of benefiting plant growth and development and maintaining soil health,controlling soil volume and water content at 20%?25%is most beneficial to soil microbial community diversity and richness.