Interactions Of Nitrogen And Phosphorus Supply And Epichlo(?) Bromicola On Growth Of Wild Barley

Wild barley(Hordeum brevisubulatum)is a kind of excellent gramineous herbage which is tolerant to salt and alkali stresses.Grass which infected by Epichlo? fungi usually has better biological yield and stress tolerance than that of without infected.However,the mutualistic symbiosis between grasses and the endophyte is affected by the external nutritional conditions.There have been a lot of reports on the stress tolerance of E.bromicola in wild barley,but little reports on how the endophyte affects wild barley under different nutritional conditions.In this study,seeds and plants of wild barley infected with endophyte and without infected were used as experimental materials,and three concentration levels of nitrogen were set: high nitrogen(15.0 mmol/L),medium nitrogen(3.0 mmol/L),and low nitrogen(0.2 mmol/L).Three concentration levels of phosphorus: high phosphorus(1.5 mmol/L),medium phosphorus(0.1 mmol/L),and low phosphorus(0.01 mmol/L).The seed of wild barley was cultured by using the nutrient solution with nine nitrogen and phosphorus.Nine nutrient solutions were also used to grow the seedlings,and the effects of E.bromicola on the germination,growth,physiology and nutrient uptake were observed.The purpose of this study was to explore the effects of E.bromicola on wild barley under the changing of a series of external nutritional conditions,so as to provide reference for the rational utilization of the endophyte in wild barley in the future.The main results obtained are as follows:1.Seed germination test found that nitrogen supply and E.bromicola infection can improve seed germination under nine levels of nitrogen and phosphorus supply.The germination index and germination potential of the seeds increased with the increase of nitrogen concentration regardless of whether they were infected by the endophyte.However,under the condition of low nitrogen supply,the germination potential of the seeds infected was significantly higher than that of the without infected seeds.The radicle length of the infected and without infected seeds was similar under the treatment of different phosphorus concentrations.Under the condition of medium phosphorus supply,with the increase of nitrogen concentration,the radicle length of the seeds without infected appeared significantly decreased under the supply of medium nitrogen,the radicle length of the infected seeds decreased significantly under high nitrogen treatment.Under the combination of nitrogen and phosphorus,the endophyte had no significant effect on the elongation of embryos compared with without infected seeds.2.The test of plant growth in the water with different nutrition liquid found that E.bromicola had no significant effect on biomass and tiller number of wild barley,the endophyte significantly increased the plant height under three combinations of nitrogen with phosphoruus.E.bromicola had significant effects on the chlorophyll content and root activity of wild barley.The chlorophyll content of the infected plants was significantly higher than that of the without infected plants under low phosphorus and low nitrogen with middle phosphorus.Endophytic fungi can significantly improve the root vigor of wild barley under low phosphorus conditions with a certain nitrogen supply.3.The contents of carbon and five mineral elements of wild barley grown under different supply of nitrogen and phosphorus combinations were determined.It was found that E.bromicola had significant effects on the contents of nitrogen and phosphorus in the aboveground and underground patrs,the contents of potassium,sodium and manganese in the underground parts,the ratio of carbon to nitrogen,carbon to phosphorus and nitrogen to phosphorus in the aboveground and underground parts.But E.bromicola had no significant effect on the carbon content in the aboveground and underground parts and the content of potassium,sodium and manganese in the aboveground part of wild barley.Under high nitrogen or high phosphorus conditions,endophytic fungi can reduce the accumulation of nitrogen or phosphorus in the aboveground and underground parts of wild barley at a certain level;under certain conditions of low nitrogen or low phosphorus,compared with without infected plants,the fungus can promote the accumulation of more nitrogen or phosphorus in the wild barley,so that the wild barley have a relatively low carbon-phosphorus ratio and carbon-nitrogen ratio.Under the condition of sufficient supply of nitrogen and phosphorus,the endophyte has a certain regulation effect on the sodium content in the underground part,so that the content of wild barley is in a relatively stable state.Compared with without ifected plants,the endophyte is beneficial for wild barley plants to absorb more manganese in the underground part.