Effects of Continuous 0.3 ppm Ozone Exposure on Decay Development and Physiological Responses of Peaches and Table Grapes in Cold Storage
Continuous ozone exposure at 0.3 ppm (v/v) (US-OSHA Threshold Limit Value for short term exposure) inhibited aerial mycelial growth and sporulation on 'Elegant Lady' peaches wound inoculated with Monilia fructicola, Botrytis cinerea, Mucor piriformis, or Penicillium expansum and stored for 4 weeks at 5 °C and 90% relative humidity (RH). Aerial growth and sporulation, however, resumed afterward in ambient atmospheres. Ozone exposure did not significantly reduce the incidence and severity of decay caused by these fungi with the exception of brown rot. Gray mold nesting among 'Thompson Seedless' table grapes was completely inhibited under 0.3 ppm ozone when fruit were stored for 7 weeks at 5 °C. Gray mold incidence, however, was not significantly reduced in spray inoculated fruit. Continuous ozone exposure at 0.3 ppm increased water loss after 5 weeks of storage at 5 degrees C and 90% RH in 'Zee Lady' peaches but not after 4 weeks of storage in 'Flame Seedless' grapes. Respiration and ethylene production rates of 'O'Henry' peaches were not affected by previous exposure to 0.3 ppm ozone. In every test, no phytotoxic injuries of fruit tissues were observed in ozonated or ambient atmosphere treatments.