ROLE OF FLOWER BUDS IN FLOWER BUD ABSCISSION IN HIBISCUS

Authors:	U. van Meeteren, H. van Gelder
Keywords:	Ethylene, auxin, ACC, darkness, postharvest handling, quality
Abstract: Plants of Hibiscus rosa-sinensis L. 'Nairobi' kept in darkness showed abundant shedding of their flower buds after 4–6 days, due to abscission at an abscission layer in the pedicels about 3 mm below the bud. Abscission was accompanied by an increased evolution of ethylene by the flower buds as well as an increased ACC and MACC content. Removal of flower buds induced abscission of the remaining pedicels under white light conditions, but delayed dark-induced abscission. In disbudded plants, time curves of cumulative abscission in darkness and under white light conditions were the same. Pedicel explants showed no abscission unless the flower bud was attached to the pedicel. Exogenous ACC induced abscission in pedicel explants. IAA drastically reduced ACC-induced pedicel abscission of explants. The results indicate that the flower bud is as well a source of an abscission- promoting-substance as an abscission-inhibiting-substance, by which the flower bud has a dualistic role in pedicel abscission in Hibiscus.
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