THE RESPIRATORY METABOLISM OF McINTOSH APPLES DURING ONTOGENY, AS DETERMINED AT 22° C

Our knowledge of the respiratory metabolism of an apple fruit has been derived heretofore from examinations of continuous respiration records, and from the study of records so short, that they give nothing but the initial rates of respiration. The former are available only for apples in the later stages of their life (1, 3); the latter provide information for apples in all stages of their ontogeny (2). A respiration record of a starving fruit may be looked upon as an expression of the physiological state, in which this fruit was present at the beginning of examination. By comparing a number of such records, produced by fruits in various stages of their ontogeny, one can follow the changes in the physiological state of a fruit during its development. By extrapolating the tendencies observed during ontogeny to the time of commercial picking in the fall, one gets a picture of the physiological drifts in a fruit at that time. Such a method of attack, based on the knowledge of the past history, can give valuable information which cannot be easily obtained from direct studies of a fruit already in storage. Since a search through the literature failed to reveal any complete sets of such records for any variety of apple, it was decided to obtain them. The McIntosh apple was selected as experimental material since it is one of our most important commercial varieties.