Application And Foundation Research Of 20% Peucedanum SC

Rice blast elicited by Magnaporthe grisea is one of the three main diseases in rice crops. Increase of resistance to pesticides, decrease in soil moisture content and pollution of environment as well as unbalance in cropland ecosystem are caused by long-term chemical protection. Hence, there is a significant meaning in finding a new path to protect rice against blast.The objectives of this study based on formal research included:The optimum technological conditions and formula of SC of 20% Radix Peucedani coumarin were determined by screening methods; Optimal applied time and concentration of SC of 20% Radix Peucedani coumarin were determined by the combination of indoor assay and field assay;Finally, physiological and biochemical mechanism of its inducible resistance was preliminarily expounded.Results were showed as follows:1. Formula screening of SC of 20% Radix PeucedaniFormula screened out by combination of experiment and experience included 20% Radix Peucedani,8% NNO+FA3000,0.1% XG,1% glycol,0.5% organobentonite and water. Quality approval demonstrated that SC of 20% Radix Peucedani was characterized by features great physical stability,eminent mobility and low cost for mass production, as well as simple processing technique.2. Control effect of 20% Radix Peucedani SC on Rice blastIn order to test inducing effect of 15% Radix Peucedani SC and determine its optimum spraying concentration,time and frequency, indoor assay was applied in indoor conditions. Indoor assay indicated the highest level of control effect was 74.22%-84.99%, using 100-400×diluent of 20% Radix Peucedani SC. However, the control effect was also affected by application time. The inducible effect was 77.03% when spraying was applied 2 days before inoculation,which was 13% higher than spraying applied 1 day before inoculation, while there is a significant decreace of inducible effect when spraying was applied 3 or 4 days before inoculation.Based on indoor assay,field assay was applied in Taojiang city where blast is prevailing.The resulte showed that on the premise of no phytotoxicity to rice, control effect of 100×,200×diluent of 20% Radix Peucedani SC were respectively 77.66%、76.28%, which was nearly consistent with 20% tricyclazole WP. However, control effect decreaced significantly when it was diluted over 400×diluent. The highest production increasing rate of rice under treatment of 100×diluent was 11.86%, which was also consistent with treatment of tricyclazole.3. Mechanism of inducible resisitance to Rice Blast.Mechanism of induced resisitance were preliminarily expounded. Enzymatic activities and variation tendency of CAT, PAL, POD, PPO and SOD were detemined. The results demonstrated that activities of POD, PPO and SOD increased significantly after treatment of 200xdiluent of 20% Radix Peucedani SC. Meanwhile, activities of POD, PPO and SOD could maintain long time after treatment. Although activity of CAT increased from 1 day to 5 day after treatment, while it ascended to control level 5 day after treatment of 100×diluent. Furthermore, activity of PAL increased not so significant as activities of POD, PPO and SOD.Thus,we could speculate that POD,PPO and SOD may conduct a leading role in inducible resistance of rice blast, while CAT and PAL may conduct a minor effect in nducible resistance of rice blast.