Preharvest application of 1-methylcyclopropene and 1-aminoethoxyvinyl-glycine affects watercore severity and volatile profiles of 'Fuji' apples stored in air and controlled atmospheres

'Fuji' apples are susceptible to watercore, a physiological disorder that occurs during maturation and can result in development of browning disorders during storage. In this study, the effects of preharvest application of the plant growth regulators (PGRs) 1-methylcyclopropene (1-MCP) and 1-aminoethoxyvinylglycine (AVG) on watercore and its subsequent effects on volatile compounds of 'Fuji' apples has been investigated. 1-MCP and AVG were sprayed one week and two weeks before harvest, respectively. Fruit were stored in air, controlled atmosphere (CA), dynamic CA (DCA), delayed CA, and delayed DCA storage at 0.5 degrees C. Storage durations were 3 and 6 months after the harvest date. The delay before CA or DCA was 30 days in air at 0.5 degrees C. PGR treatments did not affect watercore incidence but decreased its severity compared with untreated fruit. The internal ethylene concentration (IEC) of PGR-treated fruit remained very low regardless of storage regime, but treatment effects on IEC were detected. 1-MCP-treated fruit were firmer in air and CA compared with the control or AVG-treated fruit. In contrast, DCA and delayed DCA stored fruit did not soften regardless of PGR treatment and delayed treatment did not affect the rate of softening. In air storage, contents of 1-butanol, 1-hexanol, butyl acetate, hexyl acetate, propyl acetate, pentyl acetate, propyl propanoate, propyl butanoate, butyl propanoate, and butyl 2-methylbutanoate was increased in both control and AVG-treated fruit whereas, those were suppressed by 1-MCP. Production of most volatiles was also suppressed by CA and DCA storage regardless of whether the establishment of atmosphere was immediate or delayed. Ethanol and ethyl acetate content was not affected consistently by PGR treatment or storage regime.