Respiration and ethylene production in fruits and vegetables held in carbon dioxide-enriched atmospheres-effects of temperature and carbon dioxide concentration

The rates of respiration and ethylene production in various fruits and vegetables held in 0.60% CO₂ at 25 °C or 60% CO₂ at 5°25 °C were determined by an automated microcomputer system. In peaches, apples, tomatoes, and broccoli, dose-dependent decreases of O₂ uptake and C₂H₄ production were observed during treatment with various concentrations of CO₂ at 25 °C. Oxygen uptake in bananas was inhibited at 10% CO₂ and higher, whereas C₂H₄ production increased as the ambient CO₂ concentration was elevated. CO₂ concentration had little or no effect on O₂ uptake in satsuma mandarin. Oxygen uptake in lettuce at 20% CO₂ and below was similar to that under air, whereas induction of C₂H₄ production and an enhanced O₂ uptake were observed in lettuce held in 40% CO₂ and higher. Inhibition of O₂ uptake and C₂H₄ production in peaches by 60% CO₂ declined as the temperature was lowered to the range of 5-25 °C. In broccoli held in 60% CO₂, the inhibition of O₂ uptake was temperature-dependent, but C₂H₄ production was suppressed to trace level at all temperatures. The induction of C₂H₄ production and enhancement of O₂ uptake in lettuce by 60% CO₂ occurred distinctly at 25 °C, slightly at 15 °C, but not at 10 °C and 5 °C.