ISHS Acta Horticulturae 146: International Workshop on Controlling Vigor in Fruit Trees
SPUR-TYPE GROWTH MUTANTS OF MCINTOSH APPLE: A REVIEW OF THEIR GENETICS, PHYSIOLOGY AND FIELD PERFORMANCE |
| Authors: | N.E. Looney, W.D. Lane |
| Abstract:
Growth-type mutations of McIntosh apple have occurred spontaneously in several British Columbia orchards. Others have been produced by ionizing radiation. These mutants range from being quite dwarfing and very spurry to differing only slightly from standard McIntosh. They appear to differ significantly in bearing habit but only slightly in fruit quality. The Wijcik mutant (Starkspur Compact Mac) transmits its unique growth habit to a high proportion of its progeny, but most spur-type mutants do not appear to possess the Co gene. Physiological studies reveal that compared to standard McIntosh, shoot tips of McIntosh Wijcik trees are low in polar gibberellins, have high endogenous cytokinin levels and exhibit remarkable tolerance to benzyladenine in tissue culture. Abscisic acid levels and total gibberellin-like activity are lower in Wijcik seedlings possessing the Co gene. Preliminary results suggest that developing bourse buds of McIntosh Wijcik have proportionally less auxin in a conjugated form than comparable McIntosh buds. | |
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