| The PS04 isolated and screened by our group,it has broad-spectrum antifungal activity,and can also induce plant disease resistance.It is an ideal substitute for chemical fungicides.However,previous studies found that the application of PS04 directly to crops was susceptible to adverse weather conditions,leading to problems such as spray drift and serious loss of chemicals.The application of the film-forming agent not only prevents the disease spore from adhesion to the leaf surface of the crop,inhibits the development of the germ,but also improves the distribution and adhesion of the agent,increase the coverage of liquid medicine,and reduce the adverse environmental effects.Through the study on the film-forming properties of film-forming polymers CMC,chitosan,sodium alginate and starch,it was found that CMC had superior film-forming ability and better film-forming properties compared with other materials.It had high hydrophilicity and could be used as a film-forming substrate.Starch had good film-forming ability,but had poor film-forming properties and high hydrophobicity.It was suitable as a film-forming auxiliary material to improve the water solubility of the film.Through the experiment of different CMC content on film-forming properties,it was found that 2.5%-4%CMC was suitable as the optimum concentration for film formation.The different starch content was added to the CMC solution,it showed that the starch content of 1%-3% was beneficial to improve the film forming properties of the blend-film.Through the screening of plasticizers,it was found that glycerol had the greatest influence on the physical properties of the blend-film.It was found that 0.1%-0.3% glycerol was beneficial to improve the film forming properties of the blend-film.To obtain the optimum content of CMC,starch and glycerin in the blend-film solution,an orthogonal test was carried out with indicators of water vapor permeability,water solubility and light transmittance.The results showed that when the CMC content was 4%,the starch content was 2%,and the glycerin content was 0.3%,the blend-film formed by the blend-film solution had the highest water vapor permeability and light transmittance,and the lowest water solubility.Scanning electron microscopy and infrared spectroscopy analysis of the blend-film showed that the surface of the blend-film was uniform and smooth without cracks;there was a strong intermolecular force between CMC and starch,especially hydrogen bonding.there was good compatibility between film-forming polymers at the concentration.Through the screening of surfactants,all surfactants have a limited reduction in the surface tension of the liquid,and Triton X-100 has a strong ability to reduce the surface tension and exhibits good biocompatibility.A biocontrol film agent was prepared by mixing PS04 with CMC,starch,glycerin and Triton X-100.Through the antibacterial comparison test of biocontrol film agent and PS04,the results showed that there was no significant difference in the antibacterial effect between the same concentration of biocontrol film agent and PS04 on sheath blight and rice blast(P<0.05),which further indicated that the blend-film agent did not affect the biocontrol activity of PS04.Studies on the physiological activities of tomato leaves showed that the stomata size and opening degree of the leaves treated with PS04 biocontrol film agent were not significantly different from the control group during the test period.The biocontrol film agent did not produce significant chlorophyll content during the test.Through laboratory simulation of rainwater leaching test,it was found that about 28%-71% of the biocontrol film agent can be retained on the leaves of the tested plants tomato,rice,eggplant,corn and pitaya.In the control effect test of the film-forming agent,it was found that the same concentration of the film-forming agent and PS04 had the same effect on rice sheath blight.In the biocontrol test after leaching by rain,it was found that the rice treated with the biocontrol film agent finally retained 30.76% of the control effect,while the PS04 had almost no control effect.This shows that the PS04 film-forming agent has strong adhesion and rain leaching resistance. |
