Modulation Of Arbuscular Mycorrhizal Fungi On The Invasiveness Of Solidago Canadensis

Biological invasion is one of the serous ecological and environmental issues,and the government,society,and scientific research have paid more attention to this field.In recent years,the roles of soil microbes on the invasiveness of alien species have been the hot spot,among which arbuscular mycorrhizal fungi(AMF)has been the most important one because most of the alien species are mycorrhizal plants.Solidago canadensis is one of the notorious invasive weed species around the world,and highly dependent on AM fungi(AMF).However,few studies have focused on the effects of AMF on the invasiveness of S.canadensis.Aiming to solve this problem,two experiments were conducted to explore the mechanism of AMF on the invasiveness of S.canadensis.In experiment one,four levels of nitrogen treatment(0,12,24,48 g N·m-1·a-1)and two levels of native AMF inoculation treatment(non-AMF and AMF)were adopted to study the interactive effects of AMF and nitrogen deposition on the growth and nutrient uptake of S.canadensis.In experiment two,four levels of AMF treatment(inoculation with sterilized fungi,inoculation with Glomus mosseae,G.intraradices and their mixtures)and five planting types(monoculture of S.canadensis and native mycorrhizal plants Zea mays and non-mycorrhizal plants Brassica campestris,respectively and the mixculture of pair groups of S.canadensis with the two native species).The main results are as follows:(1)Compared to the non-AMF treatment,native AMF and exogenous AMF significantly increased mycorrhizal colonization and various indicators of S.canadensis,but compared to single AMF species,the growth of S.canadensis were significantly increased with the mixture inoculation of GM and GI.Obviously,mycorrhizal symbiosis somehow can improve the growth of S.canadensis,but the tradeoff between benefit and cost of S.canadensis with AMF inoculation depends on the source and species composition of AMF.Obviously,mycorrhizal symbiosis somehow can improve the growth of S.canadensis,and the tradeoff between benefit and cost of S.canadensis with AMF inoculation depends on the nitrogen availabilities in environment.(2)Under low nitrogen availability,native AMF significantly increased mycorrhizal colonization,relative growth rate,total dry weight,the total nitrogen concentration of soil and the root,stem and leaves of S.canadensis.while under the high nitrogen availability,the stimulations of AMF on the growth of S.canadensis were not significant,and compared to the growth of monoculture,the plant height,leaf number,root length,total dry weight of S.canadensis were significantly decreased,while the relative water content,Pn and root/shoot ratio were significantly increased with the inoculation of exogenous AMF under mixculture with mycorrhizal plants Z.mays;otherwise,the relative competition intensity showed that the growth of S.canadensis was inhibited while the growth of Z.mays was stimulated especially with the inoculation of G.mosseae.However,in the competitive couple of S.canadensis and non-mycorrhizal plants B.campestris,the results showed that inoculation of AMF promoted the growth of S.canadensis and inhibited the growth of B.campestris.Obviously,the effect of AMF on the invasion of S.canadensis is influenced by the nitrogen availabilities in environment and the intensity of mycorrhizal dependency of native species.