ISHS Acta Horticulturae 903: IX International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems
EFFECT OF DIFFERENT GROWTH INDUCING ROOTSTOCKS ON ALTERNATE BEARING OF 'ROYAL GALA' AND 'VISTA BELLA' APPLES |
| Authors: | J. Racsko, D.D. Miller |
| Keywords: | Malus × domestica, return bloom, fruit set, gibberellic acid, GA1, GA3, GA4, GA7, fruit quality, alternate bearing index |
| DOI: | 10.17660/ActaHortic.2011.903.54 |
| Abstract:
A field trial was carried out in an experimental apple orchard with the regular-cropping ‘Royal Gala’ and the alternate-bearing ‘Vista Bella’ over five consecutive years. Both were grafted onto M.9, MM.106, and seedling rootstocks representing dwarf, semi-vigorous and vigorous growth habit, respectively. Flowering time of both cultivars was not influenced by alternate bearing and rootstocks. The rate of fruit set was significantly higher for off-year trees on all three stocks. The amount of flower-inhibiting gibberellins (GA3 and GA7) in the seeds was significantly higher and the flower promoting GA4 was lower for on-year trees, especially on seedling rootstock. No significant differences, however, were observed in GA1 content among rootstocks. Better fruit quality parameters were usually measured for fruit from off-year trees on M.9 and MM.106 rootstocks. There was no significant differences in quality between on-year and off-year on seedling. For describing the alternate bearing habit more accurate, a modified alternate bearing index (AIm) was developed based on the flower production of the cultivars. | |
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