施氮量对烟草根际土壤微生物群落及功能的影响OA

This study aimed to investigate the effects of varying nitrogen application rates on the structure and function of microbial communities in rhizosphere soil of tobacco in Hechi tobacco planting area of Guangxi Zhuang Autonomous Region,providing a scientific refer-ence for rational application of nitrogen fertilizer in flue-cured tobacco production.The local conventional nitrogen application rate(135 kg/hm2)was used as a control(CK).Four nitrogen treatments were established:reduced nitrogen treatments N1(105 kg/hm2)and N2(120 kg/hm2),and increased nitrogen treatments N3(150 kg/hm2)and N4(165 kg/hm2).High-throughput sequencing techniques,including ITS and 16S rRNA,were employed to compare the responses of the rhizosphere soil physicochemical properties and microbial communities of tobacco to different nitrogen application rates.The results indicated that with the increase of nitrogen application rate,soil pH decreased,while the contents of soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),available phosphorus(AVP),nitrate nitrogen(NO3-N),and ammonium nitrogen(NH4-N)increased.Compared with CK,the relative abundances of dominant bacteria,such as Chloroflexi,Gemmatimonas,Sphingomonas,Micromonospora,and Candidatus_Solibacter in the N2 treatment increased.The relative abundances of dominant fungi,including Ascomycota,Basidiomycota,Penicillium,Chloridium,Saitozyma,and Ustilaginoidea also increased.Additionally,the diversity index of soil bacterial communities showed a trend of initially increasing and then decreasing with increasing nitrogen application rates,reaching the maximum under N2 treatment and the minimum under N4 treatment.In contrast,the diversity index of soil fungal communities gradually decreased,reaching the maximum under N1 treatment and the minimum under N4 treatment.The results of fungal function prediction showed that compared with CK,in the N2 treatment,the relative abundances of undefined saprotrophic fungi,ectomycorrhizal fungi,fungal parasites-undefined saprotrophs,and Clavicipitaceae endophytes-plant pathogens increased,while the relative abundance of plant pathogens-soil saprotrophs-wood saprotrophs decreased.The results of bacterial function prediction revealed that the taxonomic composition and relative abundance did not change significantly.The Mantel test results indicated that pH,total phosphorus(TP)content,and nitrate nitrogen(NO3-N)content were key factors affecting the soil bacterial community,while soil organic carbon(SOC)content was a key factor affecting the soil fungal community.In conclusion,a nitrogen application rate of 120 kg/hm2 is beneficial to nutrient cycling,the stability of the soil microbial environment,and soil health in the tobacco rhizosphere,providing useful guidance for fertilization management in the tobacco-growing regions of Guangxi.