Effects Of Microencapsulated Salicylic Acid Induced Resistance To Blue Mold In Postharvest Apple

Blue mold is one of the fungal diseases that cause serious damage to postharvest fruits.Fruits had infected by blue mold that cause certain economic losses,the most serious of fruit is apple.Apple is susceptible to be infected during post-harvest storage and transportation,and the most obvious blue mold caused by Penicillium expansum.The aim of the present experiment was to research the effect of microencapsulated salicylic acid(SAM)and SA treatment on control of blue mold,and the resistance mechanism of SAM and SA on postharvest apple("Red Fuji").Prevention and control of post-penicillosis and induction of disease resistance.In the In vitro experiment,the direct inhibition ability of 10-200 mg/L SA and SAM containing the same SA content on pathogenic bacteria was determined.In the in vivo experiment,the physiological and biochemical indexes such as quality,antioxidant and resistance of apple fruit were determined by screening the treatment conditions with better control effects under different treatment methods,inoculation time and different concentrations,and exploring SA and SAM on apple green.The resistance induction mechanism of mildew provides a theoretical basis for the better application of SA in the control of apple blue mold.The research results are as follows:(1)?-CD was used to microgelatinize SA,and the SAM was prepared by co-precipitation.The embedding rate of SAM was 90%.The SAM was micron-sized by projection electron microscopy.(2)In the in vitro bacteriostatic test,SA and the concentration of SAM containing the same quality of SA in the range of 10-200 mg/L,10-200 mg/L SA and SAM containing the same quality of SA have no obvious effect on the growth inhibition of P.expansum.However,there was a significant difference between the 200 mg/L SA treatment group and the 660 mg/L SAM treatment group and the control group.(3)In the in vivo disease resistance test,SA and SAM were more effective against P.expansum than gray mold.In the SA group,the lower concentration of 10 mg/L SA induced the phenomenon of penicillosis,and the injury time was that after 24 h was more effective than after 12 h.In the SAM group,microencapsulation improved the effect of low concentration of SA induced penicillium.As concentration of SAM increased,the effect of inoculation shows better after 24 h injury.The relative concentrations of 50 mg/L SA and 165 mg/L SAM were screened out and the treatment was inoculated with injury for 24 h.(4)In the quality test of postharvest apple,50 mg/L SA and 165 mg/L SAM treatment can maintain the hardness,SSC content,total phenolic content and DPPH clearance rate of postharvest apples,and enhance the resistance of postharvest apples.Oxidation,maintaining the quality of postharvest apples,and improving the resistance of post-harvest apples to blue mold.(5)In the induced disease resistance test of postharvest apple,50 mg/L SA and 165 mg/L SAM induced post-harvest apple resistance to P.expansum,mainly by inhibiting catalase(CAT)activity and improving oxide dismutase(SOD)activity enhances the defensive-related enzymes,such as phenylalanine ammonia-lyase(PAL),polyphenol oxidase(PPO),and peroxidase(POD),and promotes related disease manifestations.Increased activity of ?-1,3 glucanase(GLU)reduced the content of malondialdehyde(MDA)in apples and induced the resistance of apple fruit to P.expansum.(6)SAM and SA treatment of "Red Fuji" apples enhanced the ability of apples to resist P.expansum.Among them,SAM treatment of apples showed stronger induction of apple disease resistance,which may be related to wall material ?-CD.The changes in enzyme activity assay showed that SAM treatment could increase the SOD activity of antioxidant enzyme system and the PAL activity of the defense enzyme system in apple fruit.Then activity of GLU had increased,Eventually,resulted in SAM treatment is effective than SA treatment which induces post-harvest apple against blue mold.