ISHS Acta Horticulturae 520: XXV International Horticultural Congress, Part 10: Application of Biotechnology and Molecular Biology and Breeding - In Vitro Culture.
ROLE OF BUD SCALES AND PHYTOHORMONES IN THE MAINTENANCE AND RELEASE OF ENDO-DORMANCY IN FIELD- GROWN SASKATOON BERRY FLORAL BUDS |
| Authors: | Brian D. Baldwin, M. S. Bandara, Karen K. Tanino |
| Keywords: | abscisic acid, benzylaminopurine, α-naphthaleneacetic acid, Amelanchier alnifolia, bud scales, tissue culture |
| Abstract:
The influence of bud scales and phytohormones on the maintenance and release of endo-dormancy of field-grown saskatoon berry (Amelanchier alnifolia Nutt.) floral buds was examined in vitro every two weeks over three consecutive years. Test material consisted of either de-scaled or intact buds. Buds were either left attached to the stem or excised from the stem, and placed directly onto the media treatments [hormone-free, 11 μM benzylaminopurine + 0.54 μM  -naphthaleneacetic acid (BAP+NAA) or 11 μM BAP + 0.54 μM NAA + 50 μM abscisic acid (BAP+NAA+ABA)]. The influence of bud scales on bud break was dependent upon the stage of dormancy.
Before the chilling requirement was satisfied, bud break was primarily regulated by factors within the bud.
At this time, removal of the bud scale itself did not induce bud break on hormone-free media.
Removal of bud scales enhanced bud break only after the chilling requirement had been satisfied.
By contrast, the ABA medium always inhibited bud break of de-scaled buds throughout the sampling period while BAP+NAA media exerted differential effects on bud break according to whether the de-scaled bud was placed directly on the medium (always promoted bud break) or left attached to the stem (seasonal response). Excision of buds from the vascular connections of the stem did not induce bud break over all media treatments over the season.
However, the possibility of a vascular block associated with dormancy development has not been excluded by these experiments.
Although bud scales may potentially be involved in the development of endo-dormancy, this study indicates that the maintenance and release of floral bud endo-dormancy in saskatoon berry is not associated with bud scales themselves but largely by factors within the bud.
Observed enhanced bud break of de-scaled buds after the satisfaction of the chilling requirement indicates a possible physical role of bud scales in inhibiting rapid spring bud break.
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