Fabrication And Application Of Nanopesticide With Graphene Oxide As Delivery Vector Of Pyraclostrobin

Grape downy mildew is the most serious disease in the grape industry in the world and China.At present,chemical control is mainly used to prevent and control grape downy mildew.However,the long-term overuse of fungicides led to the emergence of fungicide-resistance,making the prevention and control of downy mildew of grapes more difficult.There was an urgent need to develop new fungicides to control grape downy mildew.In recent years,the application of graphene oxide（GO）as pharmaceutical carrier in medicine,environment and plant protection has become a research hotspot.In this thesis,GO was used as the carrier of Pyraclostrobin（Pyr）,a commonly used fungicide for grape downy mildew,and GO-Pyr nanopesticide formulation was developed to explore the synergistic effect of GO loaded with Pyr on fungicide.The specific research results are as follows:GO-Pyr nano-preparation was fabricated through the physical adsorption of GO on Pyr.The binding effect of GO-Pyr was characterized by transmission electron microscope,scanning electron microscope,fourier transform infrared spectrometer,diffraction of x-rays and synchronous thermal analyzer.The results showed that the composite adsorption effect of Pyr and GO at a ratio of 7:3 was the best,and the loading efficiency reached 87%.The study of p H response release kinetics and temperature response of GO-Pyr showed that under different temperatures and p H conditions,the release rate of GO-Pyr nano-preparation was slower than that of the single Pyr,which had a certain sustained release effect and effectively extended the release time of pesticide.The GO-Pyr complex is more stable than Pyr in the UV environment,and its half-life is about 31 times that of the single Pyr.The results showed that GO is a good nano carrier and can effectively delay the photodegradation of Pyr.After 2 years of storage,its physical properties were stable,indicating that GO-Pyr complex was stable in storage and conducive to storage and transportation.Contact Angle evaluation showed that GO-Pyr complex has well adhesion and diffusion ability,which is conducive to application.The indoor bactericidal activity and SR of grape downy mildew were measured to evaluate its synergistic index.Compared with the single Pyr agent,GO-Pyr complex showed better control effects on sporangium germination and bacteriostasis,and the optimal treatment concentration was 250μg/m L.Not only the concentrations of salicylic acid（SA）and JA,also the enzyme activities of PAL and chitinase increased,indicating a better stimulation and induction of the overall disease resistance of plants.Under the condition that the effective components of Pyr single agent were reduced by 30%,the disease resistance lasted for a long time.Comparing(EC₅₀)value and（SR）value,the results show that the synergistic effect of GO-Pyr nano preparation is 2.41 times that of the Pyr single agent,which improved the utilization rate of pesticide.