| Although Phalaenopsis orchids are now the second most valuable flowering potted plant according to 2001 USDA statistics, little specific quantitative information is available on the plant relating plant development to the environment. The objective of this investigation was to quantify the effects of temperature on time from spike emergence to flowering. Vegetative Phalaenopsis BL. were induced to flower then were placed into growth compartments at different constant temperatures. An initial calibration experiment was performed with P. Taisuco Smile, followed by validation experiments using several cultivars. Flower, node, and bud development rate were modeled as a linear function of development rate. Average time to flower increased from 10 to 26 weeks as temperature decreased from 26 to 14°C. At any constant temperature for any given cultivar, time to visible bud was about 60% of the total time from spiking to flower. Plants grown at 29°C failed to develop to anthesis, and most buds aborted soon after they were visible. The thermal time from appearance of the flower spike to anthesis was 769 degree days with, a calculated base temperature of 10.8°C. Node and bud development rates also increased linearly as temperatures increased. Temperatures from 17 to 26°C did not affect the number of nodes and flowers, spike height, or flower size. |
