Respiratory Response of Lemons to Ethylene1

Green and yellow lemons responded to ethylene treatment by a 2- to 3-fold increase in O 2 uptake. Maximum rates of O 2 uptake were reached some 20 hr after treatment at 25°G and both O 2 and the continued presence of ethylene were required. Following removal of ethylene, O 2 uptake declined in 2 days to a level approaching the rate before treatment. Upon retreatment with ethylene, the fruits again responded with a 2- to 3-fold increase in O 2 uptake. Ethylene stimulated the O 2 uptake of lemons in 5% and 10% O 2 even though the rates of O 2 uptake of these fruits were already limited by the low levels of O 2 . The presence of high levels of CO 2 during ethylene treatment did not suppress the ethylene-induced respiratory increase. Lemons treated with ethylene at 35°C showed typical increases in O 2 uptake. 2-Chloroethanephosphonic acid (Ethrel) stimulated the O 2 uptake of lemons more effectively than ethylene.