Effects Of The Invasion Of Three Alien Composite Plants On The Diversity Of AM Fungi And Its Feedback

Lots of invasive plant species belonged to compositae in China. Flaveria bidentis, Ambrosia artemisiifolia and Bidens pilosa are seriously exotic plant species.Exotic compositae plants spread rapidly in our country and pose a great threat to the ecological system structure and biodiversity in recent years. The effects of the invasion of the three exotic species on the diversity of AM fungi and its feedback were carried out in the common garden and greenhouse pot experiment. The dominant AM fungi in the rhizosphere soil and in the root of Flaveria bidentis were selected to study the feedback effect on competitive growth of Flaveria bidentis and Setaira viridis. The interaction relationship between the invasive plants and AM fungi was to be revealed.The results showed that the invasion of three invasive plants significantly increased the species richness and Shannon-Wiener index of AM fungi, while the species richness and Shannon-Wiener index of AM fungi in rhizosphere soil of F.bidentis, A.artemisiifolia and B. pilosa decreased in the single dominant community.The dominant species in the soil was changed, and the spore density of two dominant species of AM fungi of native plants was decreased during the invasion. The spore density of Glomus perpusillum, Glomus iranicum and Glomus iranicum increased and become the new dominant species of F. bidentis, A. artemisiifolia and B. pilosa respectively.AM fungi reduced the inhibition of F. bidentis and increased nitrogen and phosphorus content, photosynthetic nutrient use efficiency, SOD, CAT, APX activity,while decreased the content of MDA of F. bidentis when they competed with S.viridis. AM fungi enlarged the promotion of A. artemisiifolia and B. pilosa in the competition, increased nitrogen and phosphorus concentration, photosynthetic nutrient use efficiency, and APX activity, while reduced the MDA concentration of two invasive plants in competitive growth. The two dominant species of AM fungi could promote the competitive growth, increased nitrogen, phosphorus and potassiumabsorption, and enhanced photosynthetic nutrient use efficiency of F. bidentis. To sum up, AM fungi increased the competitive ability of three compositae invasive plants to some certain extent. The results provided a new theoretical basis for the soil microbial hypothesis of exotic plant invasion mechanism.