Seasonal Changes in the Circadian Rhythm of Gas Released from Harvested Cucumbers

Vegetables and fruits are known to have long-lasting biological reactions even after harvesting. Volatile components may be released as a biological response to stimulation or injury. We measured the concentrations of volatiles released from the cut surfaces of cucumbers after their harvest and analyzed the relationship between the time the cucumbers were cut and gas concentrations. The results showed that gas concentrations indicate a circadian rhythm. We previously reported that the circadian rhythm of gas concentrations was 6 hours per cycle in the summer, i.e., from the vernal equinox to the autumnal equinox, and 24 hours per cycle in the winter, i.e., from the autumn equinox to the vernal equinox. We analyzed the gas concentrations emitted from cucumber sections in more detail in this paper and found that the circadian rhythms differ among winter, spring, summer, and autumn seasons. We found that one cycle of the circadian rhythm was 8 hours in winter, 6 hours in spring, 24 hours in summer, and a mixed cycle of 24 and 12 hours in autumn.