Initiation of Rapid Ethylene Synthesis by Apple and Pear Fruits in Relation to Storage Temperature

The influence of storage temperature on the onset of rapid ethylene production was investigated for fruits of Conference pear (Pyrus communis L.) and five cultivars of apple (Malus domestica Borkh.). The time taken from harvest to rapid ethylene production was shorter and more uniform at 3 °C than at 18–20 °C for Conference pears and Golden Delicious apples. Increases in internal ethylene concentration, 1-amino cyclopropane-1-carboxylic acid concentration and ethylene production were simultaneous in Golden Delicious apples at 3 °C. When Golden Delicious apples were held at 3 °C for 48 h and then kept at 20 °C the mean time of onset of ethylene production was similar to that for apples held continuously at 20 °C. However, two periods of 48 h at 3 °C caused earlier ethylene production. Conversely, ethylene production at 3 °C was delayed by transfer to 20 °C for two periods of 48 h. Cox's Orange Pippin and other apple cultivars tended to show more synchronous ethylene production at 3 °C than at higher temperatures but the mean time of onset was either unaffected by temperature or slighdy delayed at lower temperature. Acceleration of the onset of ethylene production by low temperature was never observed in Cox's Orange Pippin apples harvested at weekly intervals from 10 August to 17 September.