Study On The Pathogenic Bacteria Of Torreya Grandis‘Merrilli’ Root Disease And Its Related Characteristics

Torreya grandis‘Merrillii’is our country peculiar economic tree species.In recent years,the development of the T.grandis‘Merrillii’industry has been more and more rapid.A large number of newly added forests have a single structure,and most of them are pure forests.They are highly susceptible to diseases and insect pests.T.grandis‘Merrillii’root rot disease is one of the most serious diseases.At present,there are few researches on T.grandis‘Merrillii’root rot disease.In this paper,the pathogen species of T.grandis‘Merrillii’root rot are estimated by Illumina PE high-throughput sequencing,isolation and identification pathogenic bacteriaof T.grandis‘Merrillii’root rot disease,biological characteristics of pathogenic bacteria,chemical control.The results of this study are as follows:1.Through the analysis of pathogenic bacteria in the root stem of infected plants,found that fungal abundance and diversity in the root of infected plants are higher than that in the stem.The abundance and diversity of fungi in the stem of seedling are much higher than that in the rhizome of adult infected plants.But the fungal abundance and diversity in seedling roots are less than that in adult,so do soil fungi.Between the root and the stem of the infected adult plant,between the adult tree and the seedling,between the soil of the adult infected plant and the seedling and between soil at different points of the same plant,fungi are more consistent in phylum level.Although the proportions vary from sample to sample,the dominant bacteria are Basidiomycota and Ascomycota.However,at the genus level,the dominant genus of each sample differs greatly between the root and stem of the infected adult plant and between the adult tree and the seedling.But between the soil of the adult infected plant and the seedling,between the soil at different points of the same plant,the fungi of Fusarium are found in each dominant genus.The various fungi found in the study can cause root rot in different species.2.Strain ZJ-10 which is isolated and purifiedfrom T.grandis‘Merrillii’pathogenic bacteria is confirmed to be the pathogenic bacterium of T.grandis‘Merrillii’root rot disease by pathogenicity test.Morphological characteristics and ITS r DNA sequence analysis revealed that strain ZJ-10 is Fusarium Solani.This is the first confirmation in T.grandis‘Merrillii’that Fusarium Solani is the cause of root rot.3.Biological characteristics of Fusarium Solani,the pathogen of T.grandis‘Merrillii’root rot disease,are observed that Fusarium Solani adapted to survive in a neutral,acidic environment.It is suggested that appropriate measures should be taken to increase the p H value of the soil to reduce the incidence of T.grandis‘Merrillii’root rot disease.Fusarium Solani to glucose,starch,lactose,fructose,gum Arabic as carbon sources can promote the growth of hypha,glucose as the most suitable carbon source.Hypha from peptone and potassium nitrate grew fastest,but on peptone mycelia grew sparser,so potassium nitrate is the best nitrogen source.With ammonium sulfate and ammonia chloride as nitrogen sources,hypha grow slowly,so ammonium sulfate and ammonia chloride are not suitable for the growth of pathogenic bacteria.Therefore,application of ammonium nitrogen fertilizer to T.grandis‘Merrillii’may reduce the incidence of root rot disease,but potassium nitrate is not suitable for application.4.Use of matrine,validamycin A,salicylic acid,FSC,the four kinds of medicament to Fusarium solani for prevention and control.Through the indoor toxicity measurement,found that FSC has the best inhibitory effect on root rot pathogens,EC₅₀is 0.06866 g/L.Of the other three pesticides,validamycin A has a good inhibitory effect on root rot pathogen,EC₅₀is 1g/L,matrine and salicylic acid inhibition effect is not ideal.