The Impact of Anti-ethylene Compounds Applied Pre- and Postharvest on the Weakly Climacteric, Bicoloured ‘Ambrosia’ Apple (Malus domestica Borkh)

Abstract Previous research has shown that all major storage disorders associated with the weakly climacteric ‘Ambrosia’ apple ( Malus domestica Borkh) increased with delayed harvest and maturity. As the fruit grade is dependent on colour development, a moderate rate of anti-ethylene products Harvista™ (preharvest 1-methylcyclopropene (1-MCP)) and Retain® (i.e., aminoethoxyvinylglycine (AVG)) were compared with a control treatment in terms of their impact on colour, maturity and storage (eight months) in this two-year optimum versus delayed harvest study. SmartFresh™ (postharvest 1-MCP) and elevated storage temperatures were added as separate postharvest storage treatments. While results should not be interpreted as a comparison of the two products, Harvista™ showed greater impact than ReTain® on ‘Ambrosia’ maturity for the rates and application timing used in this study. Harvista™ fruit were higher in starch and acidity relative to control fruit at harvest. Both the Harvista™ and ReTain® treatments impeded colour development relative to the control in Year 1 only—a poor colouration year. Both Harvista™ and SmartFresh™ fruit had superior firmness and acidity levels compared with control fruit after eight months of controlled atmosphere storage, while ReTain® fruit acidity was higher than the control group in only one out of two years. Storage disorders, led by senescent breakdown and core flush, and elevated by delayed harvest, were impacted by treatment in different ways, both positively and negatively, with complex interactions with other factors. Despite the clear connection between maturity and post-storage disorder levels in the previous optimum harvest work, delaying maturity with anti-ethylene compounds applied in the orchard did not result in a higher percentage of disorder-free fruit after storage.