Some relationships between physiology and storage behaviour in individual apples.

The relations between storage behaviour and some physiological characteristics of individual apples have been studied. The fruits of a single tree have shown considerable individual variability in the different characteristics. Improved methods have been devised for extracting samples of the internal atmosphere of apples and for measuring respiratory activity on the basis of oxygen uptake. The investigations have shown no evidence that a higher concentration of internal carbon dioxide in the apple increases its susceptibility to breakdown. Internal carbon dioxide was shown to be positively correlated with the respiration rate and protein nitrogen content. The rate of oxygen uptake measured shortly after picking was positively correlated with the incidence of bitter pit in Cox variety and of Jonathan spot in Jonathan. These disorders manifested themselves after 14 or more weeks of cool storage. The relation between Jonathan spot and fruit size in apples which were subjected to insertion of a gas pipette and to delay of ten days before cool storage was anomalous compared with uninjured fruit stored immediately. There was a strong positive correlation between the rate of yellowing and the cell volume of the fruit. Correlations found between certain characteristics and differences found between fruits of light and heavy crops were in accord with findings reported by other workers. Further investigations are now in progress which include studies of the resistances to gaseous exchange and the role of mineral elements.