Abscission of flower bud pedicels in Begonia. I. Effects of plant growth regulating substances on the abscission with intact plants and with explants

Pedicel abscission of flower buds is retarded by the presence of the bud and by IAA, the buds probably preventing abscission by auxin production. Ethylene removes the retarding effect of the buds and also accelerates the abscission of pedicel explants without buds. ABA has a small accelerating effect, gibberellic acid and kinetin are inactive. The presence of vegetative plant parts enhances the abscission rate, mainly by the supply of nutrients. The difference in flower bud abscission between three Begonia clones depends on a difference in the pedicels which is probably not hormonal in nature.