Gibberellin Effects on Inflorescence Development, Bud Dormancy and Root Development in North American Ginseng

Gibberellic acid (GA) was applied to field-grown 3-year-old North American ginseng (Panax quinqueiolius L.) between 1 and 4 times, before and during bloom in 1999. Applications of both GA and GA4+7/ four times (x4) to the developing inflorescences increased maximum pedicel length, and seed head diameter and height. Treatment with GA4+7/ increased mean and total root fresh weight linearly, whereas those treated with GA did not show similar increases. Both GA and GA4+7/ at 50, 100 and 200 mg L-1/ (x4) increased the incidence of breaking of dormancy of perennating buds with GA being twice as effective as GA4+7/. Both GA and GA4+7/ treatments resulted in an increased number of new bud initials forming per root, with the number of new initials per root increased two-fold by the GA sprays compared to GA4+7/.