Postharvest Black Rot And Controlling Fruit Decay Of Zizyphus Jujuba Mill Cv.Dongzao

Consumer demands for fungicide-free food and the development of pathogenic strains that are resistant to currently used fungicides necessitates the development of alternative methods for decay control. Zizyphus Jujuba Mill cv. Dongzao is one of the most delicious fruits in all varieties of Zizyphus Jujuba Mill. It has been developing speedly in recent years. However, the short storage life and the postharvest decay limit the industry further development.In order to study the infected pathogen and select some effective methods, we used the Zizyphus Jujuba Mill cv. Dongzao fruit grown in Hebei and Shandong Province as our study material. The pathogen which resulted in the decay at room temperature and in the poststorage at - 2 was identified and studied their characters. The potassium bicarbonate solution was applied as a "safe" postharvest treatment in controlling fruit decay and the ethylene role was also studied.The pathogenic fungi at room temperature were Alrernaria alrernaria K and Aspergillus Micheli. At -2 storage, only Alrernaria alrernaria K was identified. Aspergillus Micheli could not grow at low temperature and was not the pathogenic fungal which lead to decay in low temperature storage, but Alrernaria alternaria K could. At -2 , Alrernaria alternaria K spore germinated in 5 days and the colony diameter was 3cm in 85 days on PDA, the ethylene had no effect on it, the darkness and air could benefit to its ability of generating spore.Treatment of 3%PBC could result in shrinkage and collapse of hyphae and spores, and consequently deprived the ability of fungal to sporulate. Dipping harvested Zizyphus Jujuba Mill cv. Dongzao for 3 min. in 4%PBC delayed the decreasing of TS, TA, Vc content, induced the PAL activity and inhibited PPO activity at room temperature. The same treatment reduced fruit decay development at -2 after 95 days storage to 30%-35% compared with control and was nearly equal to the effect of chemical fungicide of Imazilil. 4%PBC had non-negative effect on the fruit qualities. Low concentration promoted fruit decay and high concentration significantly reduced fruit quality. 4%PBC may be the alternative of chemical fungicide.When treated Zizyphus Jujuba Mill cv. Dongzao with 5 l/L ethylene, the activity of PAL was induced and the incidence of fruit decay was about 80% compared with control at the beginning. Afterward, the TS, TA, Vc content decreased more quickly and PPO peak appeared earlier than control. 5 l/L ethylene promoted the fruit senescence thus advanced the decay development.