Cold-induced ethylene production of ‘Gala’, ‘Honeycrisp’, ‘NY1’, ‘NY2’ and ‘Braeburn’ apples
Cold storage is a postharvest technology applied on apple to extend storage life. However, short-term cold storage may stimulate fruit ripening, depending on factors such as cultivar selection, harvest maturity, time at low temperatures, as well as preharvest plant growth regulator treatment. Exposure of ‘Gala’, ‘Honeycrisp’, ‘NY1’, ‘NY2’, and ‘Braeburn’ to cold temperatures enhanced or resulted in similar ethylene production as that of fruit without cold storage. Longer storage period enhanced cold-induced ethylene production in ‘NY2’ and ‘Braeburn’. A warmer temperature of 10 °C also induced ethylene production of ‘Honeycrisp’, ‘NY1’, and ‘NY2’ fruit. Fruit maturity of ‘Gala’ affected the degree of response to cold storage. Ethylene production was suppressed by preharvest AVG treatment. The rates of fruit softening were enhanced by cold treatment of ‘Gala’, ‘Braeburn’, and ‘NY2’ but not ‘Honeycrisp’ and ‘NY1’, the effects of which were more significant in fruit with higher maturity at warmer storage temperature.