Responses Of Rhizosphere And Phyllosphere Microorganisms To Nitrogen Fertilizer Input In Different Tea Plant Cultivars

Nitrogen is an essential nutrient for plant growth and development,and as an important engine driving nutrient uptake and utilization,microbial-driven nitrogen uptake and utilization is significantly influenced by crop species.Tea plant（Camellia sinensis L.）is an important economic crop in China.The variety and nitrogen treatment of tea plant affect the growth and development of tea plant,and the demand for nitrogen of different varieties of tea plant is also different,and tea tree varieties have important effects on nitrogen uptake and utilization,especially the microbial response pattern and driving mechanism.Therefore,it is important to study the response pattern of microorganisms to nitrogen supply in different tea tree varieties.In this study,four tea tree varieties with different growth cycles,namely Huangjinya（HJY）,Tieguanyin（TGY）,Zhongcha108（ZC108）and Zijuan（ZJ）,were used as test materials,and two nitrogen supplies were set at 150 kg/ha（low nitrogen treatment）and 450 kg/ha（high nitrogen treatment）,respectively.High-throughput sequencing technology was used to determine and analyze the inter-root,endophytic and inter-leaf microorganisms of tea tree varieties respectively,to investigate the response patterns of inter-root,endophytic and inter-leaf microorganisms of different tea tree varieties to nitrogen fertilizer inputs,and to analyze the key drivers affecting the changes of tea tree microbial communities in combination with soil and leaf properties,with a view to providing scientific basis for regional variety introduction and fertilizer management of different varieties.The main results are as follows:1.Response of quality characteristics and nutrient contents of different tea cultivars to nitrogen fertilizer inputsHigh nitrogen input increased the ratio of phenol to ammonia in tea,reduced the content of free amino acids and tea polyphenols in tea and the accumulation of nutrients in tea,indicating that the ability of tea trees to utilize nutrients is limited,and the absorption efficiency of nutrients among different varieties is also different,and when the nitrogen application rate exceeds a certain range,it has a negative impact on the quality of tea.2.Response of inter-root microorganisms of different tea cultivars to nitrogen fertilizer inputThe inter-rhizosphere bacterial community of tea tree was dominated by Proteobacteria,Actinobacteriota,Chloroflexi,Acidobacteriota and Firmicutes;the fungal community was dominated by Ascomycota,Ascomycota and Ascomycota.Ascomycota,Mortierellomycota and Rozellomycota dominated the fungal community.Redundancy analysis（RDA）revealed that p H,TK,NH₄⁺,AK and AP were key factors driving changes in bacterial communities,while soil C/N was an important variable affecting fungal communities.The soil fungal in tea garden were mainly saprophytic,and the pathogenic fungal in ZC108 planting soil were lower than those in other varieties.3.Response of endophytic bacteria in the roots of different tea cultivars to nitrogen fertilizer inputThe endophytic bacteria in tea roots were mainly Proteobacteria,Actinobacteria,Acidobacteria and Chloroflexi.The endophytic fungal were mainly Ascomycota,Basidiomycota and Glomeromycota.The endophytic fungal were mainly saprophytic and symbiotic.RDA analysis showed that p H and NH₄⁺were the key factors driving the bacterial community,and TP and NH₄⁺were the key factors driving the fungal community.4.Response of interleaf microorganisms to nitrogen fertilizer input in different tea cultivarsTea phyllosphere bacterial community（phylum level）was mainly composed of Proteobacteria,Actinobacteria and Firmicutes.The fungal community of new leaves was composed of basidiomycetes,ascomycetes and sporophytes,and the fungal community of old leaves was composed of ascomycetes and basidiomycetes.Functional prediction showed that microbial groups were mainly involved in C and N cycle functions,and the proportion of pathotrophic fungal in the fungal function of old leaves was higher than that of new leaves.In summary,this study compared and explained the community and function of rhizosphere microorganisms,phyllosphere microorganisms and root endophytes under two nitrogen levels from the perspective of soil nutrient dynamics and microbial community structure and function of four tea cultivars under low and high nitrogen treatments.It will promote our understanding of the impact of crop varieties on the rhizosphere microbial environment and provide a basis for the accurate selection and introduction of excellent tea varieties in agricultural production practices.