|Authors: ||R.G. Lopez, E.S. Runkle, R.D. Heins|
|Keywords: ||pansy orchid, potted flowering orchids, vernalization|
The production of flowering potted orchids has increased dramatically throughout the world in the past decade.
For example, production value in the United States has increased 147% in the past six years, and in 2002 the estimated wholesale value was $105 million.
Scheduling orchid species to flower on specific dates requires knowledge of how environmental parameters regulate plant development from propagation to flowering.
In a preliminary experiment, we observed that flowering of Miltoniopsis Augres ‘Trinity’ was promoted by cool temperatures (14 to 20 oC), short photoperiods (9 hours), or a combination of both.
We performed additional experiments to determine the minimum durations of short photoperiods and cool temperatures (vernalization at 14 ºC) required for rapid and uniform flowering.
To quantify the effect of photoperiod before exposure to cool temperature, Miltoniopsis were placed under 9- or 16-h photoperiods at 20 ºC for 0, 4, 8, 12, or 16 weeks, then were transferred to growth chambers at 14 °C with a 9-h photoperiod for 8 weeks.
To determine the optimal cooling duration, a separate experiment was performed in which plants were placed under 9- or 16-h photoperiods at 20 ºC for 8 weeks and then transferred to 14 °C with a 9-h photoperiod for 0, 3, 6, 9, or 12 weeks.
Following treatments, plants were grown in a common environment at 20 °C with a 16-h photoperiod.
The flowering percentage of plants that were not exposed to short days was only 40%. Flowering percentage was greatest when exposed to short days for 4 to 8 weeks before cooling.
The optimum vernalization treatment was for eight weeks under short days.
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