Investigating structural and physiological differences between radial and diffuse types of flesh browning in Cripps Pink apples.

摘要

The Flesh Browning (FB) disorder of Cripps Pink apples can be divided into two distinct disorders, Radial and Diffuse FB, based on a number of structural and physiological differences. The type of FB observed is strongly influenced by climatic conditions during fruit growth and development. The incidence and severity of symptoms of both types of FB during storage are influenced by a combination of pre and postharvest factors. The growing degree days (GDD) accumulated from full bloom to harvest determines the type of FB observed during storage. A high risk of developing Diffuse FB occurs in seasons or districts experiencing <1200 GDD above 10 degrees C from full bloom to harvest. It is suggested that cool growing seasons desynchronise fruit ripening processes and result in fruit that are susceptible to chilling injury during storage. A high risk of developing Radial FB occurs in seasons with low GDD accumulation during the first 50 days after full bloom which have been found to be related to fruit density and gas diffusivity. The GDD during the 60 days prior to harvest maturity relates to a risk of developing chilling injury during storage and affects both types of FB. Postharvest factors which influence the development of Radial FB include storage at low temperatures (0 degrees C) and concentration of CO₂ (1%) in the storage atmosphere. The primary postharvest factor influencing incidence and severity of both types of FB is storage temperature. Fruit stored at 3 degrees C showed a significantly lower incidence of both types of FB than those stored at 0 degrees C. Scanning electron microscopic analysis was carried out to determine structural differences between the two expressions of FB.