Effects Of Different Species Of Arbuscular Mycorrhizal Fungi Inoculation On The Absorption And Movement Of Nitrogen And Phosphorus In Chinese Fir Seedlings

Arbuscular mycorrhizal fungi（AMF）,a common endomycorrhizal fungi on land,can form symbionts with 80%of plants on land.In this study,1-year-old Chinese fir seedlings were inoculated with three different species of AMF[i.e.,G.mosseae,Gm,G.intraradices,Gi,and C.etuninatum,Ce]in a greenhouse pot experiment,and the effects of different AMF speciese inoculation on plant N and P nutrient uptake,soil N and P transformation,and soil N and P loss were investigated.It can identify which AMF plays a more important role in promoting plant nutrient uptake and reducing nutrient leaching.The research results can provide a theoretical basis and reference for the sustainable development of Chinese fir plantations in China.The results are as follows:（1）AMF inoculation had no significant effects on the the height,biomass and total C content of Chinese fir seedlings,but had significant effects on root length,root surface area,root volume and plant N and P uptake,and stoichiometric ratios of C,N and P.Among them,G.mosseae inoculation had the strongest effects on root length,root surface area and root volume and N uptake.G.intraradices inoculation was more conducive to promoting P uptake at the early stage of inoculation.AMF inoculation mainly reduced the ratios of plant C:N,N:P and C:P at the early stage of inoculation,among which the lowest ratios of N:P and C:P were under the G.intraradices treatment,and the lowest N:P ratio was under the G.mosseae treatment.（2）AMF had no significant effect on rhizosphere soil total C content,but significantly reduced the total N and P contents in rhizosphere soil at the early stage of inoculation,and increased the total N and P contents at the late stage of inoculation.However,for different N and P species,AMF inoculation significantly reduced the contents of NH₄⁺-N,DON,and organic P,and significantly increased the available P content.G.mosseae inoculation significantly reduced organic P content;G.intraradices inoculation significantly increased the available P content at the late stage of inoculation.AMF significantly reduced the C,N,and P stoichiometric ratios in rhizosphere soil at the late stage of inoculation.The lowest C:N ratio was under G.mosseae treatment;The lowest N:P ratio was under the C.etuninatum treatment;The lowest C:P ratio was under the G.intraradices and G.mosseae treatments.AMF increased the soil MBC,MBN and MBP contents at the early stage of inoculation.Compared with other AMF treatments,G.intraradices inoculation significantly increased the MBN and MBC contents at the early stage and late stage of inoculation,respectively.G.mosseae inoculation significantly increased MBP content.AMF significantly increased soil acid phosphatase（AP）,acid proteinase（PRO）,arylamidase（ARY）,urease（URE）and N-Acetyl-β-D-glucosaminidase（NAG）activities.Compared with other AMF inoculations,G.mosseae significantly increased soil N-and P-related enzymes activities at the early stage of inoculation,while G.intraradices had the most significant effects on N-and P-related enzymes activities at the late stage of inoculation.AMF significantly reduced the stoichiometric ratios of soil N-and P-related enzymes at the early stage of inoculation,and G.mosseae and G.intraradices had the strongest effects on the stoichiometric ratios of N-and P-related enzymes.（3）G.mosseae inoculation significantly reduced total N leaching at the late stage of inoculation.AMF had no significant effects on the DON leaching loss,but significantly reduced the leaching losses of NH₄⁺-N and NO₃^--N.Compared with other AMF treatments,G.intraradices significantly reduced the leaching losses of NH₄⁺-N and NO₃^--N.AMF significantly reduced soil P loss.Compared with other AMF treatments,G.mosseae inoculation significantly reduced the loss of total P,dissolved P,organic P and particulate P at the early of inoculation.C.etuninatum significantly reduced the loss of dissolved P and inorganic P at the late stage of inoculation.（4）The change of soil N and P species affected plant N and P uptake.Soil NH₄⁺-N,NO₃^--N and DON were important factors controlling plant N uptake,and soil organic P and available P were the important factors regulating plant P uptake.After AMF inoculation,DON and organic P were mineralized to inorganic N（NH₄⁺-N and NO₃^--N）and available P by increasing the activities of N-and P-related enzymes,which in turn promoted plant uptake of inorganic N and available P.Therefore,plant N and P uptake reduced the contents of organic P,NH₄⁺-N、NO₃^--N and DON in the soil,and thus reduced the leaching loss of N and P.In summary,G.mosseae was more conducive to promoting the uptake of N by fir,with G.intraradices promoting P the most at the early stage of inoculation,and C.etuninatum had the greatest promotion amplitude on P at the late stage of inoculation.At the early stage of inoculation,G.mosseae was more conducive to reducing soil N and P loss,and at the later stage of inoculation,G.intraradices and C.etuninatum were more conducive to reducing soil N and P loss.