Effects of 2,4-Dichlorophenoxyacetic Acid on the Ripening of Detached Fruit

2,4-Dichlorophenoxyacetic acid was applied to the detached fruits of bananas, apples, pears, tomatoes, peppers, and persimmons and its effect on the rate of ripening of these fruits observed. The fruits were collected while still unripe and sprayed with or dipped in aqueous solutions of the acid, which contained 0.5%-2.0% Carbowax. Other fruits comparable in stage of development were treated with the acid by the liquefied-gas aerosol method, and all were then stored at room temperature. 2. Based on color changes, the ripening period of bananas was shortened from 3 to 8 days following treatment. Treated fruits attained a full yellow color and excellent flavor, even though they were subjected to drier air and lower temperature conditions than is usually maintained in their commercial ripening. Yellow Newtown apples ripened during the 2 weeks' period immediately following treatment, whereas comparable untreated apples failed to ripen in this length of time. Grimes Golden apples treated with the acid approximately 1 week before the usual picking date, when still green in color, ripened within a period of 6 days immediately following treatment. Untreated fruits picked at the same time required approximately 2 weeks at room temperature to reach the same stage of ripeness. Rome Beauty apples treated with the acid ripened 2-6 days earlier than the untreated ones, as indicated by both pressure tests and color readings. 3. The time required for Kieffer pears to change from green to yellow, when collected and treated approximately 10 days before the usual picking date, was 2-4 days less than required for comparable untreated fruits. Winter Bartlett pears ripened within a period of 8-10 days following treatment, while untreated fruits failed to ripen during this period. Treated fruits of both varieties of pears ripened more uniformly than the controls. 4. Based on color changes, the rate of ripening of fruits of tomato, pepper, and persimmon was not affected by treatment with the acid. 5. Starch hydrolysis proceeded at a more rapid rate during the ripening of treated bananas than it did during the ripening of untreated fruits, as indicated by both iodine and taste tests.