Postharvest Dips of Persimmon Fruit in Gibberellic Acid: An Efficient Treatment to Improve Storability and Reduce Alternaria Black Spot

Abstract

In Israel, fruit softening during storage and the occurrence of Alternaria black spot (ABS) disease, caused by Alternaria alternata, are the main postharvest factors that reduce quality and impair storability of persimmon fruit. The pathogen causing ABS infects the fruit in the orchard and remains quiescent until harvest, or renews its development just before harvest but mainly during storage. A preharvest spray with 50 µg·L−1 gibberellin (GA3) significantly improved fruit storability, as determined by fruit firmness and levels of ABS. While GA3 treatments have been commercially applied for more than 30 years, significant limitations of the use of the preharvest treatment like enhancing the risk of a reduced yield have been described. Recent findings suggested that postharvest dip treatments with increased concentrations of GA3 also delayed fruit softening and reduced ABS to similar levels to the commercially applied preharvest treatment in persimmon fruit stored for 3 months at 0 °C. Postharvest GA3 dip treatments at concentrations ranging from 500 to 1500 µg·L−1 were similarly more efficient in the prevention of fruit softening and ABS development than the 50 µg·L−1 preharvest spray. Present results indicated that postharvest GA3 treatment physiologically affects fruit firmness and susceptibility to ABS during storage.