| Festuca sinensis and Elymus nutans are excellent forage grass which widely distributed in the northern cold region of China.F.sinensis is normally companion species of E.nutans in natural grassland.F.sinensis was mainly infected with Epichlo(?) endophyte and formed mutual symbionts.However,when the F.sinensis growing with E.nutans,the effects of F.sinensis-Epichlo(?) endophyte symbionts on E.nutans are still unclear.In this study,when only endophyte-infected(E+)or endophyte-free(E-)F.sinensis and E.nutans growing or growing together each other,the plant growth,plant growth physiology and soil chemistry,metabolites and microbial diversity were measured in the greenhouse to explore the effects of F.sinensis-Epichlo(?) endophyte symbionts on the growth E.nutans,the role of Epichlo(?)endophyte was preliminarily revealed under the growing together.The brief results are as follows:(1)Epichlo(?) endophyte promoted the growth of the host F.sinensis.When only endophyte-infected(E+)or endophyte-free(E-)F.sinensis growing,some indices of E+ F.sinensis were significantly higher than those of E-host(P<0.05);compared with E-F.sinensis,root length,tiller number,contents of total nitrogen,gibberellic acid and cytokinin in aboveground parts of E+ F.sinensis increased by 10.0%,64.1%,30.4%,94.0% and 92.6%,respectively,and fresh and dry weight,contents of total carbon and cytokinin in underground parts of E+ F.sinensis increased by 15.3%,27.2%,3.1% and 63.0%,respectively.When E+ or E-F.sinensis growing with E.nutans,some indices of E+ F.sinensis were also significantly higher than those of EF.sinensis(P<0.05),compared with E-F.sinensis,plant height,fresh and dry weight in underground parts of E+ F.sinensis increased by 5.1%,29.0%,41.9%,respectively.Epichlo(?) endophyte also had significant effects on the growth of E.nutans,some indices of E.nutans growing with E+ F.sinensis were significantly higher than those of E.nutans growing with E-F.sinensis(P<0.05).When E.nutans growing with E+F.sinensis,dry weight,contents of gibberellic acid in underground parts and contents of total nitrogen in aboveground and underground parts of E.nutans increased by10.9%,41.5%,31.4% and 11.4%,respectively.(2)Growing with each other had significant effects on both E+ and E-F.sinensis,however,effects varied with indices.Some indices of E + F.sinensis growing with E.nutans were significantly higher than those of only E+ F.sinensis growing(P<0.05).When E+ F.sinensis growing with E.nutans,compared with only E+ F.sinensis growing,contents of total carbon,total phosphorus in the aboveground parts and total nitrogen in the aboveground and underground parts of E + F.sinensis increased by10.0%,38.4%,41.4% and 45.4%,respectively;however,plant height,tiller number,fresh weight,contents of gibberellic acid in aboveground parts,dry weight,contents of total carbon and indole-3-acetic acid in underground parts of E + F.sinensis decreased by 5.7%,22.4%,11.8%,13.5%,23.1%,5.0% and 61.1%,respectively.The results of E-F.sinensis was similar with E+ F.sinensis.Contents of total carbon in aboveground parts and contents of gibberellic acid in underground parts of E-F.sinensis growing with E.nutans were significantly higher than those of only E-F.sinensis growing(P<0.05),however,plant height,tiller number,dry weight in aboveground parts of E-F.sinensis growing with E.nutans were significantly lower than those of only E-F.sinensis grew(P<0.05).When E+ or E-F.sinensis,respectively,growing with E.nutans,plant height,tiller number,fresh weight and contents of total phosphorus in aboveground parts and dry weight in aboveground and underground of E.nutans were significantly higher than those of only E.nutans growing(P<0.05).Contents of total nitrogen in the aboveground parts and contents of gibberellic acid in underground parts of E.nutans growing with E+ F.sinensis were significantly higher than those of only E.nutans growing(P<0.05).Contents of total carbon in aboveground parts of E.nutans growing with E-F.sinensis were significantly higher than those of only E.nutans grown(P<0.05).(3)Epichlo(?) endophyte had significant effects on soil chemical properties in these treatments.Contents of total phosphorus,rapidly available potassium,alkaline phosphatase activities and sucrase activities in rhizosphere soil of only E+ F.sinensis growing were significantly higher than those in rhizosphere soil of only E-F.sinensis growing(P<0.05),however,contents of total carbon and urease activity in the rhizosphere soil of only E+ F.sinensis growing were significantly lower than those in the rhizosphere soil of only E-F.sinensis growing(P<0.05).Contents of rapidly available potassium in rhizosphere soil of E+ F.sinensis growing with E.nutans were significantly lower than those in rhizosphere soil of E-F.sinensis growing with E.nutans(P<0.05).(4)Epichlo(?) endophyte and growing with each other had significant effects on the category and relative contents of rhizosphere soil metabolites and distribution and diversity of microbe although the influences are different.When only E+ or E-F.sinensis growing,the relative contents of heterocyclic compounds,saccharides in rhizosphere soil of only E+ F.sinensis growing were significantly higher than those in rhizosphere soil of only E-F.sinensis growing(P<0.05),Contents of total carbon,total phosphorus and adenosine and derivatives,uridine in rhizosphere soil of E+ F.sinensis growing with E.nutans were significantly higher than those in rhizosphere soil of only E+ F.sinensis growing(P<0.05),however,contents of available potassium of E+ F.sinensis growing with E.nutans were significantly lower than those in rhizosphere soil of only E+ F.sinensis growing(P<0.05).Sucrase activity of E-F.sinensis growing with E.nutans were significantly lower than those in rhizosphere soil of only E-F.sinensis growing(P<0.05).The bacterial OTUs number,Chao 1 index and the relative abundance of Bacteroidetes and Actinomycetes in rhizosphere soil of only E+ F.sinensis growing were significantly higher than those in rhizosphere soil of only E-F.sinensis growing(P<0.05),however,the relative abundance of Proteobacteria in rhizosphere soil of only E+ F.sinensis growing were significantly lower than those in rhizosphere soil of only E-F.sinensis growing(P<0.05);the relative abundance of Basidiomycota of fungi in rhizosphere soil of only E+ F.sinensis growing were significantly higher than those in rhizosphere soil of only E-F.sinensis growing(P<0.05),however,the relative abundance of Ascomycota were significantly lower than those in rhizosphere soil of only E-F.sinensis growing(P<0.05).In conclusion,Epichlo(?) endophyte promoted plant growth by affecting plant nutrients and plant hormones,Epichlo(?) endophyte and growing together also indirectly affect the diversity and composition of bacterial community by influencing soil chemical properties and metabolites which may further promote soil nutrient cycling(such as nitrate nitrogen cycling)and further promoting the plant growth. |
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