Harvest maturity related changes in the cold-induced activation of 1-aminocyclopropane-1-carboxylic acid metabolism in Granny Smith apples

Changes in 1-aminocyclopropane-1-carboxylic acid metabolism in apples (Malu s domestica Borkh cv Granny Smith) were studied in relation to cold storage . Emphasis was given to the differential responsiveness of fruits to cold t reatment as a function of stage of maturity at harvest. Fruits were held at 1 or 20 degrees C for 30 days, respectively, or exposed to 1 degrees C for 10 days and then storaged at 20 degrees C for up to 30 days. Fruits at 20 degrees C showed typical climacteric behavior. Differences at 1 OC between maturity stages in ethylene production and ACC oxidase activity were abolis hed, which showed that cold treatment is an important inducer of climacteri c rise in preclimacteric Granny Smith apples. At 1 degrees C, ethylene prod uction was lower than at 20 degrees C and the maxima in production were sim ilar for all the stages of maturity, but took place at different times whic h corresponded exactly to the initial differences in harvest dates. After t he transfer to 20 degrees C, fruits exhibited similar behavior as regards e thylene production, ACC oxidase activity, and ACC and MACC levels in relati on to a harmonization process which is discussed in this study.