ISHS Acta Horticulturae 147: Symposium on Production Planning in Glasshouse Floriculture
REGULATION OF FLOWERING IN FLOWER CROPS BY GROWTH SUBSTANCES |
| Author: | A. H. Halevy |
| Abstract:
In spite of considerable research, there is only limited practical use of growth substances in regulation of flowering in flower crops. Little progress was made in this respect in the last decade. Ethylene and ethylene-antagonists are used to control flowering initiation and development more than other regulators. The most important use of ethylene in promoting flower formation is in the Bromeliaceae. Ethephon or smoke applied to iris and narcissus bulbs or plants in the field greatly stimulated flowering of plants produced from the bulbs so treated. Silver-thiosulfate (STS), an inhibitor of ethylene action, may be used to promote flower development and prevent flower bud abortion or shedding in several plants, e.g. lilies, Pelargonium, sweet peas, Schlumbergera, Agapanthus, Calceolaria, snapdragon and Delphinium. Gibberellin (GA) is used to promote flower formation in some long day and cold requiring plants. Example cases are statice, shasta daisy and Gypsophila. Surprisingly GA enhances flower formation, also in a few short day plants such as Impatiens and Zinnia. GA is applied to other plants to promote flower stem elongation and flower development as in Chrysanthemum, Liatris, and Cyclamen. Growth retardants, which act as GA antagonists, advance flower initiation mainly in woody plants, examples are azalea, Camellia and Syringa. Cytokinins can indirectly promote flower production, by increasing lateral bud breaking and branching, thus enabling flower formation in autonomously flowering plants, such as roses and carnations, if prevailing light and temperature conditions are adequate. Auxins are used to prevent flower abscission in a few flower crops. Abscisic acid is not used commercially to regulate flowering. | |
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