Kader, A.A., Department of Pomology, University of California, Davis, CA 95616, United States
Ben-Yehoshua, S., Dept. Postharvest Sci. Fresh A., Volcani Ctr., ARO, P.O. B., Bet Dagan, Israel

Exposure to superatmospheric O2 concentration may stimulate, have no effect, or reduce rates of respiration and ethylene production, depending on the commodity, maturity and ripeness stage, O2 concentration, storage time and temperature, and concentrations of CO2 and C2H4 present in the atmosphere. In some plant organs, cyanide-resistant respiration is enhanced by elevated O2 atmospheres. Ripening of mature-green, climacteric fruits was slightly enhanced by exposure to 30-80 kPa O2, but levels above 80 kPa retarded their ripening and caused O2 toxicity disorders on some fruits. High O2 concentrations enhance some of the effects of ethylene on fresh fruits and vegetables, including ripening, senescence, and ethylene-induced physiological disorders (such as bitterness of carrots and russet spotting on lettuce). While superatmospheric O2 concentrations inhibit the growth of some bacteria and fungi, they are much more effective if combined with elevated (15-20 kPa) CO2, which is a fungistatic gas. (C) 2000 Elsevier Science B.V.