Influence Of Arbuscular Mycorrhizal Fungi On Plant Reproduction Characteristics,Yield And Quality Under Warming And Nitrogen Deposition In Songnen Meadow

Arbuscular mycorrhizal(AM)fungi is one of the most important soil microorganisms which improve the adaptation of plants to environmental stress.Global changes,such as,elevated temperature and nitrogen(N)deposition have been influcing the ecological processes,not only plant community,but also underground soil microbial community(eg.AM fungi,bacteria,etc).However,the influence of AM fungi on plant reproduction characteristics and yield quality under global changes is still unclear.In this study,a field experiment study was conducted in the Songnen grassland with three factors,warming,N addition,and AM fungi suppression,one dominant species Leymus chinensis,two subordinate species Phragmites australis and Puccinellia tenuiflora were selected.The the plant sexual and asexual reproduction characteristics,plant yield and quality were studied,which can help us understand the mechanism that AM fungi determine plant community structure and maintain plant productivitt in the Songnen grassland under warming and N addition.The main results are as follows:(1)Under warming and N addition conditions,AM fungi promoted the reproduction of L.chinensis,and AM fungi improved the sexual reproduction in the aerial part by increasing heading rate,seed setting rate,and thousand-grain weight.AM fungi reduced the negative effects of warming and N deposition on the reproduction of P.australis by improving their heading and seed setting capabilities.Contrast to L.chinensis and P.australis,AM fungi significantly declined the small flower number of of P.tenuiflora,butincreased seed setting rate and thousand-grain weight.(2)AM fungi significantly improved the asexual reproduction ability of L.chinensis under nitrogen addition,but had no impact under warming.Under warming and N addition,AM fungi decreased the asexual reproductions of P.australis and P.atenuiflora.(3)AM fungi promoted the reproduction distribution of L.chinensis and P.atenuiflora,inhibited the reproduction distribution of P.australis.AM fungi can significantly reduced the biomass of P.australis,and have no significant effect on the height of plants.AM fungi significantly reduced the crude protein content of plants;in the presence of AM fungi,warming and N addition improved forage quality by increasing plant crude protein content and reducing the acid detergent fiber content.In summary,The results showed that AM fungi significantly affected plant sexual and asexual reproduction characteristics under warming and N addition,but the AM fungi effect varied among different species,and the effect of AM fungi on the sexual and asexual reproductions of L.chinensis was highly stronger than those of P.australis and P.atenuiflora,which can partly explain the mechanism how AM fungi determine plant community structure in Songnen grassland.In addition,AM fungi might alleviate the negative impact of warming and N deposition on forage yield and quality by increasing protein content and reducing fiber content.