Isolatiaon Of Endophytic Fungi Of Acacia Confusa Merr.and Its Screening And Application On The Growth Of Acacia Confusa Merr.

Endophytic fungus can alleviate various adversity environment and promote the resort to plant growth and development,its role has been confirmed by our predecessors.Acacia confusa Merr.is an potential species in the coastal protection forest.To promote its growth under the special Climate conditions and development of soil in the coastal sandy sites environment,it's very necessary to study on the endophytic fungi of Acacia confusa Merr.In this study,after the separation and purification different organs of Acacia confusa Merr.endophyte fungi,the dominant fungi including phosphate solubilizing fungi are screened out.The effects of endophyte infection on Acacia confusa Merr.are determined under common conditions and low phosphorus conditions by measuring indicators to analyze whether endophyte fungi can promote the host growth and development and alleviate the harmness of phosphorus stress or not.The main findings are obtained as follows:1.One hundred and thirty nine kinds of endophytic fungi were isolated from the healthy organs of Acacia confusa Merr sampled in September,2014,including 61 strains in stems,47 strains in roots,only 31 strains in leaves.2.Endophytic fungus role in the growth-promoting effect of Acacia confusa Merr.(1)Analysing the height,ground diameter,root-shoot ratio and biomass of Acacia confusa Merr.,we find AE strains could significantly promote the growth of height,ground diameter and B strain and C strain could significantly promote the growth of root-shoot ratio and biomass of Acacia confusa Merr.(2)Analysing the effects of endophytic fungi on photosynthesis by measuring chlorophyll content and chlorophyll fluorescence parameters,CE strain strengthen the photosynthesis ability of seedlings to the maximum extent among the selected strains.(3)The result of C\N\P\K elements analysis showed that DE strains are the most conducive strains to the increase the content of C\N\P\K in Acacia confusa Merr.seedlings.3.Endophytic fungus role in Acacia confusa Merr.growth under low phosphorus stress.(1)The effect of endophytic fungus on Acacia confusa Merr.biomass under low phosphorus stress:Analysing the diameter and seedlings height,we found that the four strains and one mixed-strain all could significantly promote the growth of seedlings height and biomass.I strain had stronger ability in storaging plant biomass.(2)Endophytic fungus role in Acacia confusa Merr.photosynthetic characteristics under low phosphorus stress:measuring and analyzing the chlorophyll content and chlorophyll fluorescence parameters and we found that five phosphorus solubilizing fungus showed no significant effect in alleviating the harmness of phosphorus stress in promoting host photosynthetic characteristics.(3)Endophytic fungus role in Acacia confusa Merr.physiological ecology under low phosphorus stress:measuring and analyzing the leaf relative conductivity?MDA content and soluble protein content in the cell,we found that H strain had the best effect on decreasing the degree of cell injuring and improve the soluble protein content.Measuring and analyzing the APA activity in the leaf?root and soil,we found that F strain had a better effect in improving the APA activity in the leaf,FH strains had a better effect in inducing root secreting APA,N strain had a better effect in improving the APA activity in the soil.(4)Endophytic fungus effect on nutrient content in Acacia confusa Merr.under low phosphorus stress:measuring the content of C\N\P\K in the aboveground part and underground part,we found that F strain could effectively improve the C\N content and FH strains could better improve the P content.Phosphate solubilizing fungi showed no significant effect on absorbing K.