Ethylene Evolution and Flowering of Cold- and GA-treated ‘Redwing’ Azaleas

Abstract

Gibberellic acid (GA)-treated ‘Redwing’ azaleas ( Rhododendron spp.) flowered in half the time required for cold-treated plants. Visual plant quality and flower uniformity were equal in both treatments. Ethylene evolution of buds was monitored in plants receiving cold treatment, receiving GA application, or remaining in the greenhouse without a dormancy-breaking treatment. Ethylene was not detectable in untreated plants or in cold-treated plants during cold treatment. Ethylene in buds was detected on the 4th day after removal from the cooler and was found to correspond to ethylene generation in GA-treated plants.