Observation of watercore dissipation in 'Braeburn' apple by magnetic resonance imaging

Following unusually high temperatures during the 1997/98 growing season, a significant incidence of watercore was observed in the New Zealand 'Braebur n' crop (Malus domestics) for the first time. Serial proton magnetic resona nce imaging was subsequently used to monitor the characteristics of disorde r amelioration in individual fruit during 3-week and 15-week storage trials (0-0.5 degrees C). Symptoms (water-soaked appearance of flesh around the l ocule area and extending into the cortex) in "slightly" affected fruit (>0. 5 cm(2) affected or <25% of the equatorial cross-section area affected) gra dually dissipated in 3-5 weeks leaving fruit with normal appearance and tas te. Extracellular fluid in fruit classified as "severely" affected (>25% of the equatorial cross-section area affected) also dispersed completely, but over a longer time-6-8 weeks. However, the internal appearance of some sev erely affected fruit was unacceptable after 15 weeks of coolstorage. It is not clear whether the presence of cavities and brown mealy flesh was attrib utable to watercore or other factors associated with the anomalous seasonal conditions. Lines of 'Braeburn' in which a high incidence of severe waterc ore is present at harvest thus represent high risk for long-term storage.