Abstract: It’s difficult to restore vegetation in limestone area, due to the severe and thin soil layer of the limestone habitat. However, some plants adaptive to limestone soil like Broussonetia papyrifera grow in this habitat, the reason maybe that these plants possess rhizospher microbes like arbuscular mycorrhizal fungus. In this paper, an experiment was conducted on B. papyrifera seedling by disposals of single inoculation, co-inoculation and noninoculation used three mycorrhizal fungus，which are Glomus.mosseea, G. versiforme and G. diaphanum. Some photosynthesis indexes are measured to study the physiological responses in this experiment after 3 months. The results show that, the disposal of inoculated AM fungus improve the growth of host plants about height ,ground diameter, leaf area while compareing with the none. The pcolonization rate root increase by inoculation AM fungus. The net photosynthesis rate(Pn) increase significantly in each disposal inoculated AM. Transpiration rate(E) and stomatal conductance(Sc) decrease in this disposal by G. diaphanum while the others represent significant enhancement compared with non-inoculation. By inoculation, the photosynthesis-water-comsumtion decrease significantly in host plants, it indicate that the water use efficiency(WUE) improve by inoculation. The content of Chl a and Chl b increase extremely significant.

Key words: AM fungus, Broussonetia papyrifera, photosynthesis, transpiration, stomatal conductance, photosynthesis-water-comsumtion