Screening Of Straw Degraing Fungi And The Effects On Soil Biochemical Based On Long-term Experiment

Straw returning is the main routes of straw resource reuse,which has been widely implemented in Huang–huai–hai Plain,and has been regarded as an important measure for improving soil fertility and increasing grain yield.The degradation of straw directly affects the soil nutrient cycle and crop growth.How to accelerate straw degradation is one of the important problems in the process of agricultural production.Fungi are the main contributors to cellulose decomposition,so the screening and development of straw degrading fungi are particularly important.Agroecosystem is affected by many environmental factors,and the results of the same agricultural measures in different years are often inconsistent,which determines that the longterm experiment has good reproducibility and authority in agricultural research.Based on the long–term fertilization experiment,the changes of soil physicochemical and biological properties and the differences of soil fungal community structure under different fertilization treatments were investigated,and their relationships between soil properties and fungal community structure were explored.The results showed that under the condition of combined application of chemical fertilizer,long-term organic addition and straw returning significantly improved soil fertility.Long–term straw returning reshaped the community structure of soil fungi,especially the abundance of Chaetomium,Trichoderma,Penicillium and other beneficial fungi were enriched.After a long-term repeated location experiment,the fungal community structure in farmland soil was well domesticated and tended to be stable.Therefore,isolating beneficial fungi stimulated by long-term straw returning hasimportant potential applicationsUsing carboxymethyl cellulose agar medium(CAM),the straw degrading fungi in straw returning soil were screened,isolated and identified by dilution plate method.Following the molecular biological identification,Congo–red–CAM was used to evaluate the cellulose degradation ability of the isolated fungal strains.The isolated 64 strains of straw degrading fungi were all belonging to Ascomycota,and they were distributed in 7 families and 11 genera,respectively,including Neriaceae,Aspergillaceae,Trichocomaceae,Hypocreaceae,Chaetomiaceae,Pleosporineae and Sarocladiaceae.Among them,fast cellulose degrading fungi has 19 strains,and medium/slow cellulose degrading fungi were 19 /12.Fast cellulose degrading fungi were mainly classified as Chaetomium,Trichoderma,Penicillium,Fusarium,Aspergillus and Talaromyces.According to the cellulose degradation ability of the selected fungi and their abundance changes in long-term fertilization treatment,two fungal strains,Mortierella capitata and Chaetomium uniseriatum,were selected for pot experiments to explore their effects on soil nutrient transformation and crops growth.(1)The content of soil available phosphorus increased significantly in inoculation treatment.(2)M.capitata can directly promoted crop growth by up regulating the expression of genes related to primary metabolism,and indirectly stimulate crop growth by optimizing the rhizosphere bacterial community structure and increasing the abundance of Glomeraceae.(3)C.uniseriatum significantly improve the degradation rate of straw and promote its nutrient release.(4)C.uniseriatum stimulated the expression of hormone response related genes in maize roots,which were benefit toe crop growth.