Preliminary Study On Epicuticular Wax And Postharvest Disease And Resistance Of Blueberry Fruits

Blueberry are worldwide favorable fruits among consumers because of abundant antioxidant compounds,such as anthocyanins and flavonoids,having some special bio-functions,like anti-aging,anti-oxidation and anti-cancer.However,due to blueberry are susceptible to microbial infection,fruits usually occurs postharvest deterioration during storage process,resulting in serious economic losses of blueberry industry.The blueberry skin is covered with white wax layer,which plays an important role in regulating the fruit development,ripening and storage performance.At present,there are few researches on blueberry fruit epicuticular wax and postharvest diseases at home and abroad.In this paper,blueberry as experimental material,the epiculticular wax of fruits was removed by bluetack and the effect of epicuticular wax injury on the postharvest diseases and storage quality was studied.The primary fungal pathogens which cause postharvest decay of blueberry during storage were isolated and identified using morphological and molecular methods.The biological characteristics of the isolated strains were further investigated.Blueberry fruit inoculated with B.cinerea was to discuss the effect of epicuticular wax injury on the postharvest disease resistance.The main conclusions are as follows:(1)Blueberry fruits accelerated the decay rate and water loss rate after epicuticular wax injured during poetharvest storage.I was found that fruit firmness decreased along with the storage.Epicuticular wax injury increased the total phenol and MDA,and enhanced the enzyme activity of POD,PPO,PAL,SOD and CAT.Intact epicuticular wax could maintain TSS and TA,and has higher activity of resistance related enzymes,improving the disease resistance of fruit.Therefore,epicuticular wax injury could reduce the fruit storage quality and aggravate fruit deterioration during storage of blueberry.(2)Five kinds of primary fungal pathogens which caused postharvest decay of blueberry were isolated and identificated based on the morphologies of colony and conidial and the rDNA-ITS sequence analysis:B.cinerea,T.viridescens,P.cecidicola,P.polonicum and P.expansum.The biological characteristics of the isolated strains were further investigated and the results showed that the suitable culture media and temperature for the five strains were blueberry extract-glucose media and 25-30?,respectively.The optimal carbon and nitrogen source was fructose peptone for B.cinerea?P.cecidicola and P.polonicum,of which the effects of light on the mycelia growth were significant.The optimal nitrogen source for T.viridescens and P.expansum was yeast extract powder,the carbon source was sucrose and soluble starch,respectively,but the light has insignificant effects on.The results could provide the basis for the control of the postharvest disease of blueberry(3)The Epicuticular wax injury has closely relationship with disease resistance of blueberry.Blueberry was more susceptible to infection of pathogen after epicuticular wax injured,causing a large area of decay during postharvest storage.Epicuticular wax injury increased decay rate and disease indexes,induced the resistance related enzymes activity of PPO,SOD,POD,CAT and PAL.However,intact epicuticular wax could maintain the higher enzyme activity,effectively resist the invasion of pathogenic bacteria,and improve disease resistance of postharvest fruits.