Study On The Effect Of Arbuscular Mycorrhizal Fungi On Enhancing The Salt Tolerance And Nitrogen And Phosphorus Absorption Of Gleditsia Sinensis And Zelkova Serrata

In order to verify whether inoculation of arbuscular mycorrhizal fungi in woody plants can alleviate the harm of salt stress on plants,and to explore whether AMF can improve the salt tolerance of plants by promoting the absorption of nitrogen and phosphorus.In this study,three purchased mycorrhizal fungi GM1,GM2 and GO were inoculated in self-cultured aseptic Gleditsia sinensis and Zelkova serrata seedlings for salt stress pot experiment.The effects of AMF on the inoculation of two tree species under salt stress were studied by measuring the root infection rate,seedling height,ground diameter,root characteristics,related enzyme activities and chlorophyll fluorescence characteristics.The nitrogen and phosphorus absorption by AMF under salt stress was studied by measuring total nitrogen and phosphorus content in plant root,stems and leaves,and total nitrogen,alkali-hydrolyzed nitrogen,total phosphorus and available phosphorus content in rhizosphere soil.The main results are as follows:(1)Salt stress had no significant effect on GM1 and GM2,and their infection rates were all above 90%.However,the GO infection rate of Gleditsia sinensis decreased with the increase of salt concentration.When the salt concentration was 150mmol/L,the infection rate was 12.23% lower than that under no-salt stress.Salt stress can significantly affect the infection rate of AMF to Zelkova serrata,but with the change of salt concentration,the infection rate of GM1 and GM2 has no significant change,while that of GO has significant change.For Gleditsia sinensis,under salt stress,the infection rates of GM1,GM2 and GO were reduced by 14.59%~16.25%,5.55%~8.39% and 10.86%~30.14%,respectively,compared with those under no-salt stress.Inoculation of AMF can significantly increase the growth of Gleditsia sinensis in height and diameter.At the same salt concentration,the growth of Gleditsia sinensis inoculated with GM1,GM2 and GO was 3.08~31.10 times,2.94~31.73 times and 2.94~11.63 times,respectively,and the ground diameter growth was 2.59~3.25 times,2.69~3.50 times,and 2.37~2.67 times than which were not inoculated with Gleditsia sinensis.The height growth and ground diameter growth of Zelkova serrata under salt stress were increased by inoculation of AMF,but not significantly.The inoculation of AMF can promote the root growth under salt stress of two tree species,and effectively alleviate the harm of salt stress to two tree species.Compared with the three kinds of mycorrhizal fungi,GM1 and GM2 had better growth improvement effect under salt stress than GO.(2)Under salt stress,inoculation of AMF increased the NR activity of leaves of two tree species,decreased the NR activity of roots of Gleditsia sinensis,and increased the NR activity of roots of Zelkova serrata;Under low salt stress,AMF had no significant effect on GR activity of leaves of two tree species.Under high salt stress,inoculation of AMF could significantly increase GR activity of leaves of two tree species,but both had no significant effect on GR activity of roots of two tree species;Under low salt stress,AMF had no significant effect on the NOX activity of leaves of Gleditsia sinensis,while under high salt stress,AMF could significantly increase the NOX activity of leaves of Gleditsia sinensis.Under salt stress,inoculation of AMF could significantly increase the NOX activity of leaves of Zelkova serrata,as well as the NOX activity of roots of two tree species;Under salt stress,inoculation of arbuscular mycorrhizal fungi can improve the ability of light absorption of two tree species,alleviate the harm of salt stress,and achieve the purpose of improving the salt tolerance of plants.(3)Inoculation of arbuscular mycorrhizal fungi can increase the total nitrogen and total phosphorus content in roots,stems and leaves of two tree species under salt stress,and the effect of GM1 and GM2 is higher than that of GO.(4)Under salt stress,the content of total nitrogen and total phosphorus in the rhizosphere soil of two tree species was not significantly affected by AMF inoculation,but the content of alkali-hydrolyzed nitrogen in the rhizosphere soil of two tree species was decreased;With the increase of salt concentration,The content of available phosphorus in the rhizosphere soil of Gleditsia sinensis inoculated with GM1 and GM2 increased;With the increase of salt concentration,the content of available phosphorus in the rhizosphere soil of Zelkova serrata inoculated with AMF increased gradually,and the effect of GM2 was the most obvious;Under low salt stress,AMF had no significant effect on electrical conductivity in rhizosphere soil of Gleditsia sinensis,under high salt stress,GM1 had no significant effect on the electrical conductivity in rhizosphere soil of Gleditsia sinensis,while GM2 and GO had significant effect on the electrical conductivity in rhizosphere soil of Gleditsia sinensis,while at the same salt concentration,AMF had no significant effect on the electrical conductivity in rhizosphere soil of Zelkova serrata;Under salt stress,the inoculation of AMF had a certain effect on the content of total chloromycin in rhizosphere soil of two tree species,but it was not significant.In general,AMF can improve the salt tolerance of Gleditsia sinensis and Zelkova serrata,improve the ability to absorb nitrogen and phosphorus,and promote the absorption of nitrogen and phosphorus.