Abstract: A greenhouse pot-experiment was carried out to investigate effects of indigenous and exogenous arbuscular mycorrhizal fungi(AMF) on phytoremediation of PAHs-contaminated soil by Medicago sativa and Lolium muhiflorum.Inoculation of exogenous Glomus caledonium 36 enhanced significantly AMF infection rate of M.sativa and L.muhiflorum(P<0.05),and plant biomass as well,while inoculation of indigenous AMF alone or together with G.caledonium 36 did not show any positive effect on the AMF infection and plant biomass,and even decreased AMF infection rate of L.muhiflorum at its seedling stage.Planting M.sativa and L.muhiflorum stimulated PAHs degradation(P<0.05),which reached 42.3% and 41.1%,respectively on D60 after inoculation with G.caledonium 36,suggesting the significant effect of the strain.However,inoculation of indigenous AMF did not have such effect.Inoculation with indigenous AMF and G.caledonium together did not show much effect on M.sativa in the soil,but did on L.muhiflorum degrading PAHs on D60.A significant positive correlation was observed between degradation rate of PAHs in the soil and AMF infection rate in the plant roots(P<0.05),suggesting that AMF infection can increase the phytoremediation efficiency of PAHs-contaminated soil.

Key words: arbuscular mycorrhizal fungi, polycyclic aromatic hydrocarbons(PAHs), phytoremediation, Medicago sativa, Lolium muhiflorum