摘要 : 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... 展开 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 (AI_m) was developed based on the flower production of the cultivars. 收起