Storage of Tomatoes in Low Oxygen Atmospheres Inhibits Ethylene Action and Polygalacturonase Activity

The effect of low concentrations of O2 (1%) with or without the application of exogenous ethylene (10 μl/l) on the production of endogenous ethylene, the activity of polygalacturonase (PG), and the ripening of tomato fruits during storage for three weeks at 20°C and four weeks at 10°C, followed by one week under ambient conditions (25°C) was studied. The internal ethylene concentration in the fruits stored under low O2 at 10 or 20°C was low during storage and increased only when fruits were transferred to ambient conditions. The application of exogenous ethylene to fruits stored under low O2 at 10 or 20°C did not induce autocatalytic ethylene synthesis. By contrast, the internal ethylene concentration of fruits stored in air was high at 20°C and somewhat lower at 10°C. Under low O2 conditions, PG activity was low and the fruits remained firm and green throughout storage, whereas, during storage in the air, PG activity increased and the fruits softened and developed their characteristic red color.