Effects Of Different Fertilization On Community Structure Of AMF In Major Farmland Crops Soils

Arbuscular mycorrhizal fungi(AMF)can form a root symbiosis with approximately 80%of the terrestrial plant species,which are one group of very important soil functional microorganism.However,how the fertilizations influence AMF diversity and structure is still not well established.Understanding the community structure of AMF in different crops in response to fertilization is a great significance for modern sustainable agriculture.In this study,high-throughput sequencing approach was employed to investigate the variation on AMF community in maize rhizosphere in northeast of China and in soils with rice-wheat rotation ecosystem of Jiangsu province with different fertilizations.Moreover,Mantel test,RDA and other multivariate statistical analysis measures were used to explore the effects of different environmental factors on AMF community structure.Four treatments about maize experiment in northeast of China were designed,including:NK(N 165 kg/ha,P2O50 kg/ha,K20 75 kg/ha),NPK(N 165 kg/ha,P205 60 kg/ha,K2O75 kg/ha),NPKM(replacing 20%inorganic nitrogen by organic nitrogen,total nitrogen consists with NK and NPK),M(100%organic nitrogen).While in the experiment with the rice-wheat rotation system in Jiangsu Province,five treatments,with five different nitrogen levels but the same phosphate and potash fertilizer,were set.For wheat,the nitrogen levels contained 0 N kg/ha(NO),50 N kg/ha(N50),100 N kg/ha(N100),200 N kg/ha(N200),300 N kg/ha(N300),and for rice season,two cultivars including super rice variety(liangyou 3218,SN)and inbred variety(Zhen rice No.11,ZN)Were employed with nitrogen levels of 0 N kg/ha(NO),90 N kg/ha(N90),180 N kg/ha(N180),270 N kg/ha(N270),360 N kg/ha(N360).The primary results were as follows:For maize,different fertilizations had different effects on the AMF community structure in maize rhizosphere,showing by the AMF Bdiversity variation of maize rhizosphere.Concomitantly,organic fertilizer in the maize rhizosphere soils was the key factor to result in changes of AMF community structure(r2=0.8608,p=0.002).And the following significant influencing factor was N-fertilizer(r2 = 0.6472,p = 0.022)while the third significant influencing factor was P-fertilizer(r2 = 0.5048,p = 0.04).At the same time,the Eethyl acetate-dissolved organic matters composition displayed the similar variation trend with the structure of AMF community.The application of organic manure activated more species of AMF in maize rhizosphere via change the organic chemical compositions.For wheat reason in Jiangsu,the inputs of different nitrogen levels significantly affected the structure of AMF community.Available-K(r2 = 0.567,p = 0.003)and microbial biomass carbon(r2=0.5966,p = 0.004)were found to be the major causes of the changes on AMF community structure in the soils.For rice season,different nitrogen levels also significantly affected the AMF community structure in rice soil,but the rice cultivars had no significant impact on AMF community structure in rice soil.Soil organic matter(r2 = 0.5062,p = 0.001),soil total N(r2=0.3764,p = 0.003),AK(r2 = 0.3315,p = 0.009)and pH(r2= 0.2875,p=0.014)were the main reasons to influence the AMF community structure.As showed by structural equation model,different nitrogen levels was able to directly affect the AMF diversity and community structure in rice soil,but the cultivars can only indirectly affect the diversity and community structure via impacting the soil physical and chemical properties.Taken together,no matter under which planting system,different fertilization regimes have impact on soil AMF community to certain extent.Nevertheless,the main driving forces in different plant system with different fertilization regimes on impacting the AMF community could not be the same.However,AMF diversity was always reduced with the increase of nitrogen inputs.So,we can reduce the amount of nitrogen inputs in order to improve the ecological benefits of AMF.