| Orchids are currently the second most valuable flowering potted floriculture crop in the United States. However, the commercial potential of the vast majority of orchids has not been explored primarily due to insufficient knowledge of how to regulate growth and flowering. A series of experiments was performed to determine the effects of photoperiod and temperature on growth and flowering of six orchid hybrids. Brassia Rex 'Sakata', Degarmoara Winter Wonderland 'White Fairy', Miltassia Charles M. Fitch 'Dark Monarch', and Odontocidium Tiger Crow 'Golden Girl' did not flower in response to a range of photoperiods (10 to 24 hours) or cool temperature (8 to 23°C) treatments. In Miltoniopsis Augres 'Trinity', flowering percentage was greatest (≥90%) and was most rapid when plants were exposed to 9-h photoperiods for 4 to 8 weeks at 20°C and then vernalized under short days at 14°C for 8 to 12 weeks. Similarly, flowering of Zygopetalum Redvale 'Fire Kiss' was promoted most when exposed to short days at 23°C for eight weeks followed by eight weeks of vernalization at 11 to 14°C. Additional studies were performed to quantify the effects of temperature on pseudobulb development, time to flowering, and flower longevity. Thermal time models were developed for these processes and are presented. |
