Preliminary Study On The Antibacterial Effect And Application Of 4-Ethylphenol Against Phytophthora

Oomycetes,represented by Phytophthora,seriously harm the production of agricultural products,resulting in the decline of the quality of grain and other agricultural and sideline products,causing great losses to the national economy.At present,chemical pesticides are widely used in the prevention and control of Phytophthora disease,which is easy to produce drug-resistant strains.At the same time,environmental pollution and ecological damage can not be ignored.Therefore,plant fungicides with high efficiency,low toxicity,low residue and environmental friendliness have become a research hotspot.In order to define the source of plant volatiles to prevent and control the application prospect of plant disease,in this paper,the volatiles are measured and screening of soybean,determine 4-Ethylphenol as the research object,and verify its toxicity to the growth of mycelium,sporangium and zoosporium formation,and zoosporium germination of Phytophthora sojae and Phytophthora nicotianae,measured after 4-Ethylphenol treatment of mycelial growth and morphology change;The control effects of 4-Ethylphenol on soybean root rot and tobacco black shank were measured by soil treatment.The results are as follows:1.After inoculation of soybean leaves with susceptible material(Williams)and resistant material(Williams-82),gas chromatography-mass spectrometry(GC-MS)analysis showed that the volatile amount of 4-Ethylphenol in resistant material was much higher than that in susceptible material,and 4-Ethylphenol was selected for verification.2.The experiment proved that 4-Ethylphenol can inhibit the production of zoosporangium and zoospores of Phytophthora,and the higher the concentration of4-Ethylphenol,the stronger the inhibition effect.The inhibition rate of 4-Ethylphenol(120mg/L)on sporangium formation and zoosporium formation of Phytophthora sojae were 95.2%and 100% respectively.The inhibition rate of zoosporium and zoosporium formation of Phytophthora nicotianae was 100%.The inhibition rate of 150 mg/L 4-Ethylphenol on sporangium formation was 100%.4-Ethylphenol also had a certain inhibitory effect on zoospores germination of Phytophthora.The minimum inhibitory concentration of4-Ethylphenol against Phytophthora sojae was 120 mg/L,and the minimum inhibitory concentration of 4-Ethylphenol against Phytophthora nicotianae was 150 mg/L.3.4-Ethylphenol can inhibit the growth of mycelia.When the concentration of4-Ethylphenol reaches 150 mg/L,the inhibition rate of mycelia growth of Phytophthora sojae and Phytophthora nicotianae is 100%.4-Ethylphenol had obvious inhibitory activity on mycelial growth of Phytophthora,and with the increase of the concentration of 4-Ethylphenol,the inhibitory activity on mycelial growth of Phytophthora was enhanced.When the concentration of 4-Ethylphenol reached 120 mg/L,the mycelial growth of P.niacae was 0,and the inhibition rate of mycelial growth of P.niacae was 100%.The results of the antibacterial aging test showed that 4-Ethylphenol had no significant decrease in the inhibitory effect against Phytophthora within 60 hours under the minimum inhibitory concentration.After treatment for 60 hours,the inhibition rate of 4-Ethylphenol on the mycelial growth of Phytophthora sojae and Phytophthora nicotianae remained above 90%.4.The microscopic observation proved that 4-Ethylphenol changed the morphology of Phytophthora mycelia.Compared with the control group,the growth of 4-Ethylphenol treated mycelia was disorderly,with increased terminal branches,and the formation of branches was closer to the top,and the formation of sporangia was inhibited.The determination of intracellular material leakage showed that 4-Ethylphenol could destroy the cellular structure of Phytophthora.The leakage of DNA and protein of hypha treated with 4-Ethylphenol was significantly higher than that of the control,and the higher the concentration of 4-Ethylphenol,the higher the leakage was.5.The infection test of soybean hypocotyl showed that 4-Ethylphenol could inhibit zoospores from infection of soybean hypocotyl.The zoospores of the control treated Phytophthora sojae could attach to the hypocotyl of the yellowized seedlings and grow a large number of hyphae for infection.The zoospores treated with 4-Ethylphenol greatly reduced the ability of adhesion and infection.6.The plant safety test of 4-Ethylphenol showed that low concentration of 4-Ethylphenol could slightly promote soybean growth,while certain concentration of 4-Ethylphenol had no obvious inhibitory effect on soybean growth,tobacco germination and normal growth.The amount of adding bacteria in pot experiment of soybean and tobacco was determined by pathogenicity experiment of pathogenic bacteria on tested plants.Potted experiment showed that 4-Ethylphenol can effectively control soybean root rot and tobacco black shank disease,the higher the content of 4-Ethylphenol,the lower the incidence of disease,the better the relative control effect.The control effect of 0.2 g/ dm~2 4-Ethylphenol on soybean root rot was100%,and that of 0.05 g/ dm~2 4-Ethylphenol on tobacco black shack was 100%.