Ethylene Production, Respiration, & Internal Gas Concentrations in Cantaloupe Fruits at Various Stages of Maturity.

In studying the relationship between ethylene production and the climacteric rise in respiration exhibited by ripening fruits, it was not possible to determine when ethylene production begins until the advent of gas chromatography. This technique makes available quantitative measurement of ethylene concentrations at or below the threshold of physiological activity. Burg and Thimann (3, 4) were the first to apply the method to studies of fruit ripening; ethylene was determined with an especially sensitive thermal conductivity detector (2). In recent work, Meigh et al. (11, 12), using the more sensitive flameionization detector, measured ethylene concentrations as low as a few parts per billion. Gas chromatography was used in this study of cantaloupe fruits (Cucumis melo L. var. reticulatis) to assess the rate of ethylene and carbon dioxide evolution and concurrent internal concentrations of ethylene, carbon dioxide, and oxygen. For the ethylene determinations, a highly sensitive flame-ionization detector was used, and the other gases were analyzed with a thermal conductivity detector. Results from two experiments are reported. In the first experiment, analyses were performed on the internal atmospheres of cantaloupes harvested at different stages of development, and in the second. changes in the rate of production of ethylene and carbon dioxide and in the composition of the internal atmosphere were followed in harvested mature melons as they progressed from the preclimacteric through the climacteric stages of ripening. While a few values have been reported for the respiratory rate of cantaloupes (13), these data are the first to present a pattern of respiration and establish clearly the presence of the climacteric in this fruit.