STUDIES ON APPLE ROOTSTOCK SELECTIONS RELATING RESPIRATION RATES TO AN ANATOMICAL METHOD OF PREDICTING DWARFNESS

Abstract

The respiration rates of leaf disks and root tips of apple rootstock selections are related to the per cent of bark in the root which has been shown to be an index of dwarfing potential. In 1958 and 1959 significant regression coefficients were shown between the respiration rate of leaf disks and the per cent of bark in the roots. A highly significant regression coefficient was obtained between the respiration rate of the root tips from rooted softwood cuttings and the known per cent of bark in the root of the parent plant. The data indicate that the respiration rate of leaf disks or root tips would be a satisfactory measure of dwarfing potential within a closely related series of apple rootstock selections.