Book Description

Phalaenopsis orchids have one of the longest greenhouse crop production times, averaging 18 to 24 months from propagation to sale. The long production time is expensive for commercial producers because every stage of production requires a controlled environment in the form of a greenhouse or growth chamber. Different quantities of red and blue light were applied to Phalaenopsis flower spikes in order to observe differences in elongation and spike morphology. The total number of flowers on each plant was not affected by light quality. Although differences in spike length were not dramatic, production time differed between treatments. Flower spikes in the pure red treatment emerged earliest. Treatments consisting of 20 [mu]mol m−2 s−1 blue light and 180 [mu]mol m−2 s−1 red light were quickest to bloom. In an additional experiment, flower spikes were exposed to white light or combinations of monochromatic red and blue light while leaves were exposed to white light. None of the treatments affected spike length during the first four weeks, but after 12 weeks the spikes exposed to red, blue, or red and blue light were shorter than those exposed to white light. LED lighting has the potential to influence spike growth and production time of Phalaenopsis. The effect of lighting cycles on Phalaenopsis flower spike growth and development was tested by exposing plants to light cycles of 20, 24, or 28 hours, each divided into equal periods of light and dark. Significant differences were observed in overall growth of flowers. The results show that flower count was greatest in plants exposed to the 20-hour cycle. The 28 hour treatment resulted in the lowest flower count. None of the treatments affected time to flower opening. Further studies entailing manipulation of light cycles are warranted.