The interaction and effect of two species of arbuscular mycorrhizal fungi on the growth of Astragalus sinicus L. at different pH level
不同pH水平下两种菌根真菌对紫云英生长的影响及其相互作用

The effects of two species of arbuscular mycorrhizal fungi, Glomus mosseae and Gigaspora margarita to Astragalus sinicus biomass under the condition of four pH level ranging from acidic to neutral (4.3, 5.1, 5.8 and 6.8) were investigated in a pot experiment. Some important parameters reflecting the colonization rate of AMF were tested, including TB coloration, the enzyme activity of succinate dehydrogenase (SDH) and alkaline phosphatase (ALP). The result showed that there was an apparent relativity between plant biomass and the colonization rate and the enzyme activity of AM fungi. The colonization rate increased with the rising of pH value when the plants were inoculated with Glomus mosseae alone or with mixed strains, but when the plants were inoculated with Gigaspora margarita alone, the colonization rate was the highest at the level of pH 5.8 and then decreased at 6.8. In mixed inoculum experiment, the interaction of the two fungal species at different pH level was detected by nested PCR with special primers gm1 and gig1. At lower pH level(4.3-5.1), most of roots were infected by Gigaspora margarita and Glomus mosseae apparently decreased the colonization of Gigaspora margarita. At higher pH level(5.8-6.8), most of roots were infected by Glomus mosseae, and Gigaspora margarita effectively increased the colonization rate of Glomus mosseae. None of the roots were simultaneously infected by the two fungal species.