Reduced fruit quality throughout cold storage is a major stakeholder-identified factor limiting production and marketability of the profitable apple ‘Honeycrisp’ in the Mid-Atlantic. ‘Honeycrisp’ is known to be a chilling sensitive cultivar when cooled immediately after harvest, therefore fruits are submitted to a postharvest conditioning treatment (10ºC for 7 days) prior to cold storage (3ºC). However, conditioning exacerbates the expression of bitter pit, rendering the fruit unmarketable. Moreover, maturity at harvest is a critical factor affecting apple fruit quality as well as susceptibility to chilling stress. Ethylene, the primary hormone related to hastening fruit maturity, can be regulated via the use of preharvest ethylene regulators. We aimed to characterize and compare the effects of different preharvest ethylene regulators on ‘Honeycrisp’ fruit maturity, quality and chilling sensitivity during postharvest. Three preharvest ethylene regulators with different modes of action were applied based on manufacturer’s recommendations, including 1- methylcyclopropene (1-MCP, Harvista), aminoethoxyvinylglycine (AVG, Retain), Ethephon (Ethrel) and a control. Fruits were harvested at two maturity stages: at the anticipated commercial harvest (CH) and one week after CH (CH 1). After harvest, in each case, fruit were submitted to conditioning (10ºC for 7 days) and then stored at 3ºC. Fruit from all 8 treatments were evaluated at harvest, and after 8, 16 and 24 weeks of storage at 3ºC, followed by a shelf-life period (7 days at 20ºC). Our results show that preharvest ethylene regulator treatments impacted fruit maturity and quality of ‘Honeycrisp’ apples during storage. Ethylene production was reduced in 1-MCP and AVG treated fruit, with the latter showing the lowest values throughout storage during both harvest dates. Concurrently, 1-MCP and AVG treated fruits displayed a higher flesh firmness as well as a greener background color (as indicated by higher IAD values) compared to Ethephon- treated and control fruit. Skin blush was negatively affected by 1-MCP and AVG applications, which were maintained throughout postharvest, with AVG-treated fruit exhibiting the significantly lower values. Effects on starch pattern indices and soluble solids contents were inconsistent. Chilling sensitivity, through the presence of soft scald, was not observed, but 1-MCP treated fruit presented the highest bitter pit incidence, followed by AVG-treated fruit, while Ethephon and control fruit displayed the lowest. This study contributes to understand how preharvest ethylene modulation influences ‘Honeycrisp’ apple maturity and quality throughout storage.
