Using the respiration rate of 'Pink Lady' apples as an indicator of their susceptibility to the flesh browning disorder

'Pink Lady' apples (Malus domestica) are susceptible to flesh browning in storage. The symptoms of this disorder are browning in a radial pattern from the core into the cortex and softening of the fruit. The disorder is sporadic in nature with only some growers in some seasons being affected. It is likely that the disorder is the result of a combination of factors. Other work has shown that 'Pink Lady' apples are susceptible to CO 2 injury. Fruit with severe browning symptoms at the end of storage had 35% higher respiration rates and a greater than 60% reduction in the ability to produce ethylene than fruit with no browning. Fruit that had high rates of respiration at 80 days had a higher risk of developing browning symptoms later in storage. High fruit respiration rates indicate high internal CO 2 concentration (assuming that fruit permeances are equal). This work shows that it may be possible to use the rate of respiration as a diagnostic tool to determine the susceptibility of a sample of fruit to flesh browning later in storage.