Respiratory Response of Citrus Fruit to Ethylene Treatment

Abstract

Several kinds of citrus fruit, including satsuma mandarin (Citrus unshiu Marc.), hassaku orange (Citrus hassaku Hort.) and natsudaidai (Citrus natsudaidai Hayata), responded to 10ppm ethylene treatment by increases in CO₂ evolution at 20°C.
When ethylene treatments were continued for more than 3 days, maximum rates of CO₂ evolution were reached during days 1 to 3, the rates of CO₂ evolution declining there after.
When 1-day treatments with ethylene were repeated every other day, the fruit showed an increase in respiration rate to the first 3 to 5 treatments, but responded little to the subsequent treatments.
When the treatment of 3 days of ethylene and 1 day of air was repeated, the 2nd and the 3rd cycles did not induce any response in the fruits.
When the treatment of 2 days of ethylene and 1 day of air was repeated, the first 2 cycles induced a response but subsequent ones had little effect.
When the treatments with ethylene for 3 or 6 days and air for 3 days were repeated, the fruits responded to the 2nd cycle.
In view of these results, it was thought that citrus fruit(non-climacteric type of fruit) has a certain ability to respond to ethylene for a limited time and that this ability can be recovered during a period of several days without treatment.