Abstract
In order to obtain the primary data for determining maturity of Golden Delicious, Starking Delicious and Fuji apples, fruit samples were collected at 7-14 day intervals with a total of 4 to 6 harvests during the period of maturation and ripening. The rates of respiration and C2H4 evolution, and the internal C2H4 concentration were measured for 7 to 20 days beginning 1 day after harvest.
1. As harvest was delayed, the rise in respiration began sooner after harvest, and late harvested Golden Delicious and Starking Delicious apples showed a high rate of respiration at 1 day after harvest, which was associated with a subsequent increase, resulting in attainment of almost a climacteric peak at the last harvest. However, in late harvested Fuji apples, although the rate of respiration at 1 day after harvest became high, an initial decline in the rate was followed by a rise in respiration, which was less pronounced with delayed harvest, eventually disappear ing in the last harvest.
2. The increase in C2H4 evolution was observed during the climacteric rise in respiration, but in late harvested Fuji apples, except for the last harvest that showed an increase in C2H4 evolution without any respiratory upsurge, it occurred before the onset of the rise in respiration.
3. As harvest was delayed, the rapid increase in internal C2H4 concentration began sooner after harvest, and late harvested Golden Delicious and Starking Delicious apples showed a high internal concentration of C2H4 at 1 day after harvest, while late harvested Fuji apples showed a small increase in the internal concentration of C2H4 at 1 day after harvest, followed thereafter by a rapid increase in most fruits.
4. The internal concentration of C2H4, which increases rapidly as a rapid increase in fruit C2H4 production begins during the period of maturation and ripening, is considered to be capable of serving as an index of maturity.
