Epstein, E., Institute of Horticulture and Department of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel
Ackerman, A., Institute of Horticulture and Department of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel

Indole-3-butyric acid (IBA) greatly enhanced the rooting of an early-flowering variety of protea, Leucadendron discolor, but had very little effect on a late-flowering variety. IBA transport and metabolism were studied in both varieties after incubating the cuttings in 3H-IBA. More of the radio-label was transported to the leaves of the easy-to-root variety than the difficult-to-root (35-45% and 10%, respectively). IBA was metabolized rapidly by the cuttings of both varieties and after 24 h most of the label was in the new metabolite. However, free IBA (about 10%) was present in the cuttings during the whole period up to the time of root emergence (4 weeks). More free IBA was accumulated in the base of easy-to-root cuttings, while in the difficult-to-root variety most of the IBA was found in the leaves. The metabolite was identified tentatively as an ester conjugate with a glucose. It is possible that IBA-glucose serves as a source for free IBA, and the difference between the varieties is a consequence of the free IBA which is released, transported and accumulated in the site of a root formation. © 1993 Kluwer Academic Publishers.