Effects Of Nano Copper Oxide And Nano Zinc Oxide With Different Concentrations On Microbial Communities In Sorghum Rhizosphere Soil

In recent years,nano metal oxides have been widely used as new nanomaterials in agriculture.The nanometallic oxides in agricultural fertilizer components are prone to accumulate in farmland,posing potential risks to agricultural ecosystems.However,research on the impact of nano metal oxides on the microbial community of plant rhizosphere soil in black soil areas is still not detailed.Therefore,this study used sorghum（Longza 17）,a major coarse grain crop in the north,as the experimental plant.Two nano metal oxide materials were treated in potted black soil:nano copper oxide（CuO NPs）and zinc oxide（ZnO NPs）,with each treatment consisting of three concentrations:low concentration(100 mg·kg^-1),medium concentration(200 mg·kg^-1),and high concentration(400 mg·kg^-1).Studying the effects of CuO NPs and ZnO NPs on soil bacterial and fungal microbial communities provides a theoretical basis for understanding the response of soil ecosystems to nano metal oxides in fertilizers.The main research results of this article are as follows:（1）Under the same concentration conditions,CuO NPs have a stronger effect on bacterial Alpha diversity in sorghum rhizosphere soil than ZnO NPs.PERMANOVA analysis showed that there was no significant difference in the impact of two types of nanometallic oxides on bacterial community Beta diversity,but the concentration of nanometallic oxides was the main factor affecting Beta diversity.Compared with CuO NPs,ZnO NPs have an inhibitory effect on bacterial OTU enrichment with increasing concentration.The same concentration of CuO NPs and ZnO NPs has the greatest impact on the two bacterial communities,Acidobacteriota and Chloroflexi.Analysis of the impact of soil chemistry properties on bacterial community showed that available phosphorus significantly affected the bacterial community structure of CuO NPs and ZnO NPs treatment.In addition,available potassium also had a significant impact on the bacterial community structure of CuO NPs treatment.In the bacterial co-occurrence network,CuO NPs and ZnO NPs reduce the relative abundance of bacterial ecological groups.The bacterial community assembly and ecological processes of all treatments with CuO NPs and ZnO NPs 100 were dominated by deterministic and variable selection processes,respectively.Among the bacterial functional flora,CuO NPs significantly affected the functional flora of carbon cycle and nitrogen cycle,while ZnO NPs significantly affected the functional flora of carbon cycle.（2）Under the same concentration conditions,CuO NPs have a stronger impact on the diversity of fungal Alpha in sorghum rhizosphere soil than ZnO NPs.PERMANANOVA analysis shows that the concentration of nano metal oxides and the type of nano materials are the main factors affecting the structure of bacterial communities.Compared with the control,CuO NPs 400 and ZnO NPs 200treatments significantly increased fungal alpha diversity.Different concentrations of CuO NPs and ZnO NPs significantly affect fungal Beta diversity.Among fungal communities,Ascomycota is most affected by CuO NPs and ZnO NPs.Analysis of the impact of soil chemistry properties on fungal community showed that SOM,AN and AK significantly affected the fungal community structure of CuO NPs,and SOM,AN,AP and AK significantly affected the fungal community structure of ZnO NPs.In the fungal co-occurrence network,CuO NPs and ZnO NPs reduce the relative abundance of fungal ecological groups.The assembly process and ecological process of fungal communities in CuO NPs and ZnO NPs are mainly random and incomplete processes,respectively.Functional prediction shows that CuO NPs have no significant impact on the fungal functional microbiota,while ZnO NPs only significantly affect the fungal functional microbiota of fungal parasites,plant pathogens,and plant saprophytes.In summary,different concentrations of CuO NPs and ZnO NPs affect the structure of soil bacterial and fungal communities,and CuO NPs are more capable of stimulating changes in soil microbial communities than ZnO NPs.The response of soil bacterial and fungal communities to CuO NPs and ZnO NPs also varies with changes in concentration.The impact mechanisms of different concentrations on the assembly and symbiotic network of soil fungal and bacterial communities in CuO NPs and ZnO NPs are different.Both nanometallic materials and concentrations can affect soil community composition and co-occurrence networks.