At day 1, the O2 levels decreased significantly and a rapid accumulation of CO2 inside the packages due to fruit respiration for both treatments (Fig. 2). The peak of CO2 production in treated fruit appeared earlier than in the control, and the peak value of treated fruit was significantly higher than that of the control, indicating that ethephon stimulated ripening immediately after treatment. The results were similar to those of Antunes et al. (2000), who observed that the respiration rate of ‘Hayward’ kiwifruit with 1000 μL L−1 propylene at 20 °C increased earlier and produced higher CO2. Afterwards, the O2 concentrations with ethephon treated kiwifruit changed slightly and were significantly lower than those in the controls. This was due to oxygen entering the package from the environment being quickly depleted in treated kiwifruit that have higher respiration rates than that in controls at the same gas transmission rates of the film. Ben-Arie and Sonego (1985) and Cia et al. (2006) found that gas concentrations inside packaging plastic materials are directly related to the gas transmission rates of the films. Ethephon treatment improved ripening by increasing respiration rates.