Active Substances Extraction Of A168 Strain And Toxicity Against Rhizoctonia Solani

Integrated rice-duck farming system is a good technical measure for rice ecological cropping and organic rice production, which could efficiently control the damage made by pest in the paddy and improve soil fertility, meanwhile increase rice production and quality, make rice safe, ensure paddy increment, increase peasant income, reduce environmental pollution and protect agricultural eco-environment. This system could significantly prevent the occuence of rice sheath blight---a kind of serious rice disease whic causes great losses annually.The best extraction of the extracted active substance against R.solani was studied with the ratio of ethyl acetate and broth,the culture time of A168 strain and the extraction time of ethyl acetate and broth based on the antagonistic strain of rice sheath blight A168. The result showed that with the ratio of ethyl acetate and broth 4:1, the temperature 28℃, continuous ultrasonic extraction of 36h, the A168 strains active substances were extracted the best. Active substances through the A168 strain of rice sheath blight reached the indoor toxicity, EC50 value 2.15mg/mL, EC90 value 237.86mg/mL, showed that A168 strain of active substances on the inhibitory effect of rice sheath blight better. A168 strains active substances can inhibit the growth of mycelium, the outflow of cell wall damage to the cytoplasm, protein synthesis and other means of mycelium decreased virulence, inhibiting the occurrence of rice sheath blight.