The Pesticide Active Study Of Botanical Compound Thymol To Fusarium Oxyporum F.sp.Niveum

Watermelon is one of the world's top ten fruits,China has the largest watermelon acreage in the world.In recent years,watermelon wilt increasing year by year with larger planted area of watermelon,and has a direct impact up to more than 80%.Jiangsu Province Academy of Agricultural Sciences of Production Environment and Put-inSubstances Safety Laboratory discovered that thymol has good field control effect on watermelon wilt.This thesis studies thymol forms processing,the inhibitory mechanism of thymol to Fusarium axyporum f.sp.niveum and the feasibility of soaking watermelon.The formulation of the 5%thymol EW,a preliminary understanding of thymol against Fusarium oxyporum f.sp.niveum and the soaking concentration are identified in this paper.It laid a foundation to further study the use of thymol.1.By studing the effects of thymol on the growth morphology of hypha,spore germination,the physiological and biochemical characteristics of Fusarium oxyporum f.sp.niveum and the inoculation experiments.The results showed that the thymol affected the morphology of hypha significantly,mycelium cell enlarged,protoplasm contracted,extravasation,cell membrane permeability increased,leading to death because of the cell disruption.The physiological and biochemical characteristics of Fusarium oxyporum f.sp.niveum also showed significant changes after treated with thymol,cell membrane permeability,hyphae glycerol content,malondialdehyde(MDA),ROS and pyruvate were significantly increased,but the protein,DNA,ergosterol content was significantly reduced.,and the inoculation was significantly reduced.By measuring the physiological and biochemical characteristics,it provided important reference information to clarify the mechanism of thymol on Fusarium oxyporum f.sp.niveum.2.The optimum formulation of 5%thymol emulsion in water(EW)was developed by the phase transfer method through the screening of the emulsifiers,thickeners and antifreeze:thymol mass fraction of 5%;solvent mass fraction of 15%ethanol;emulsifier SC-102 6%wt;mass fraction of 1%propylene glycol antifreeze;thickener agar 0.2%wt;co-surfactants n-butanol and water-soluble active agents azone mass fraction of 1%and 2%,with double-distilled water up to 100%.The indexes of the thymol EW was up to grade which made by the above formulation.3.The seeds and seedlings of watermelon were handled by the various concentrations of thymol.This thesis studied the effects of thymol on the watermelon seed germination,include the growth,the chlorophyll content,the root activity and the change of antioxidant enzymes in watermelon.The results showed that the changes of germination energy,germination percentage,germination index and vigor index had no significant difference less than 300 mg/L thymol concentration,whereas it markedly decreased with the rising of the thymol concentration.The effects of thymol on the growth and chlorophyll content were same to the germination.When the thymol concentration was less than 300 mg/L,the growth and chlorophyll content were no significant difference compared with the control(except for the fresh weight).Under the treatment of thymol soaked seeds the root activity showed the trend of increase-decrease with the increase of thymol concentration.The root activity significantly increased compared to the control in 100 mg/L thymol concentration.In 200 mg/L thymol concentration the root activity was higher than the control,whereas there was no significant difference compared to the control.The root activity decreased with the rising of the thymol concentration.The SOD activity significantly increased less than 300 mg/L thymol concentration,whereas it markedly decreased with the rising of the thymol concentration.The POD activity had the same trend as the CAT activity.In 100 mg/L and 200 mg/L thymol concentration the POD and CAT activities were higher than the control,whereas there was no significant difference.From the correlations analysis of seed germination parameters and physiological and biochemical indexes with the thymol concentrations knew that it was a negative correlation relationship between seed germination parameters and physiological and biochemical indexes with the higher thymol concentration.All the results showed that the germination and growth were not affected less than 300 mg/L thymol concentration being used to prevent the watermelon wilt disease.