Ethylene production and respiration by Granny Smith apples were inhibited by treatment with 20% CO(2) for 2 hours. A similar effect was observed in tissue slices when treated at either 0 or 25 degrees C.The inhibition continued even after an extended aeration period. There is also an inhibition of ethylene emission in tissue slices incubated with exogenous 1-aminocyclopropane-1-carboxylic acid (ACC).In general, CO(2) treatment increased the ACC content of the tissue. These observations are consistent with the idea the action of CO(2) is directed toward the enzyme system responsible for the conversion of ACC into ethylene.