Abstract:A greenhouse study was conducted to learn the effect of introduced or indigenous mycorrhizae species on the growth and phosphorus uptake of Pennisetum flaccidum,which was a sand fixation plant on the grassland of the Tibetan plateau.The result showed that the mycorrhizal dependency of Pennisetum flaccidum was very high(166.4% at the(average) level) and all the AM epiphytes(or epiphyte combination) had a significant infestation effect on the radication of Pennisetum flaccidum.The plant biomass and phosphorus uptake was greatly increased by inoculation of arbuscular fungi(correlation coefficients were 0.7465 and 0.6000 respectively).The hyphae contribution to the plant phosphorus uptake was significant with the contribution amount and rate being 3.2～11.6 mg/pot and 61.5%～85.3% respectively.The phosphorus uptake varied among the different inoculation treatments which appeared as Glomus intraradices>G.mosseae + G.etunicatum + G.intraradices + Scutellospora erythropa>G.mosseae-1(introduced mycorrhizae species)>G.mosseae + G.intraradices + Scutellospora calospora>G.mosseae2(indigenous mycorrhizae species)>G.etunicatum In addition,the influence degree of AM epiphytes on shoot,root biomass and P uptake rate was significant different.The inoculation effect of treatments with mixture of several indigenous fungi was much higher than the single indigenous fungi inoculation treatment.