OCCURRENCE OF ABSCISIC ACID AND GIBBERELLINS IN ORCHID FLOWER

Abstract

The major. ether-soluble growth inhibiting substance detected by the wheat coleoptile straight growth test in the extracts from both the flower buds and the mature flowers was separated by thin-layer chromatography, and was indentified as abscisic acid (ABA)-like component by Rf values in three different solvent systems used. The level of ABA-like activity in neutral ether fractions of both flowers extracts was pot significantly different. whereas, the ABA-like activity in the acidic ether extracts of flower bude was greater than that of mature flowers. Moreover, 'Bound'-ABA wae detected in the extracts of the mature flowerr but not in that of the flower buds. Based on the chromatographic behavior and the lettucehypocotyl bioassay, gibberellin-like activity was detected in the acidic ethylacetate fractions of flower buds extract but not in that of the mature f1owers. There was no detectable gibberellin- like activity in the neutral ethylacotate fraction of the flower extracts.