Abstract
With autumn production, seedlings of easy-boltingEustomacultivars tend to bolt before or during low temperature treatment. This results in plants that have not reach adequate size length to ensure being high quality cut flower stems. In an attempt to avoid this problem, we treated easy-boltingEustomacv. Candy White and Candy Marine with Uniconazole alone or in combination with gibberellic acid to investigate their influence on the bolting and flowering with the following results. (1) Uniconazole (50 ppm) inhibited bolting and kept seedlings rosetted through the experimental period. (2) Gibberellic acid (GA, 100 ppm) completely reversed uniconazole inhibition and induced rapid bolting within 2 weeks with or without low temperature treatment (10°C, 4 weeks) . (3) Uniconazole-treated seedlings remained rosetted, but produced much smaller flowers than normal ones, which indicated that GA was not involved in flower bud differentiation but involved in flower development ofEustomacultivars. We concluded that premature bolting of easy-boltingEustomacultivars could be avoided by uniconazole treatment and that uniconazole-induced rosetting could also be reversed to bolting by GA at desired time.
