PHYSIOLOGICAL ASPECTS OF SUMMER PRUNING

D.C. Ferree, S.C. Myers, C.R. Rom, B.H. Taylor
Severe summer pruning of container grown apple and peach trees resulted in increased net photosynthesis (Pn) and transpiration (Tr) of basal leaves within 3–10 days compared to similar leaves on unpruned control trees. The effect persisted for approximately 30 days and was not evident on lightly pruned trees. A second cycle of increased Pn occurred on peach trees receiving a second summer pruning. Orientation of potted apple trees at 45°, 90°, or slow continuous rotation at 90° resulted in similar Pn increase and/or prevention of Pn decline with age compared to trees severely summer pruned. Abscissic acid-like activity in axillary apple buds 6 days after summer pruning was 54% lower than the levels of buds of unpruned trees.

The greatest reduction in total dry weight due to 50% shoot removal in summer pruning occurred in stems followed by leaves with the least reduction in roots (ca. 35%) of both apple and peach trees. Generally increased severity or delay in time of pruning result in proportionately greater reductions in tree dry weight. Summer pruning did not consistently influence total non-structural carbohydrate content of either peach or apple. In apple roots sorbitol, glucose and fructose levels generally increased as amounts of summer pruning increased with no effect on sucrose or phloridzin compared to unpruned trees. These results will be compared to other studies in the literature in an attempt to explain the physiological basis of summer pruning.

Ferree, D.C., Myers, S.C., Rom, C.R. and Taylor, B.H. (1984). PHYSIOLOGICAL ASPECTS OF SUMMER PRUNING. Acta Hortic. 146, 243-252
DOI: 10.17660/ActaHortic.1984.146.28
https://doi.org/10.17660/ActaHortic.1984.146.28

Acta Horticulturae