Effect of night break treatment on growth and flowering in Dendrobium phalaenopsis
2011
Shimomachi, T. | Mitsumizo, T. | Matsuzono, R.
In the present study, the effect of night break treatment on growth and flowering in Dendrobium phalaenopsis was investigated, in order to develop a method to control flowering. Three cultivars of Dendrobium phalaenopsis (‘Burana Pink’, ‘Burana Diamond’ and ‘Artemis’) were used in the present study. Dendrobium phalaenopsis plants were cultivated in the greenhouse until they had a lead bulb and four buck bulbs each, then they were grown for 15 weeks in a growth chamber under 10/14 h light/dark cycles with the room temperature at 30/20°C in light/dark period, relative humidity at 70% and the light intensity at 200 μmol m-2 s-1 photosynthetic photon flux (PPF) at the growing point. One night break treatment of one hour duration was scheduled in the middle of the dark period. The growth of the plants was measured by parameters such as lead bulb length and maximum diameter, number of leaves and day of flowerings, and compared to the control plants. Night break treatment affected the timing of the floral stem appearance. Flower bud formation was delayed for approximately 10 days in ‘Burana pink’ and advanced by 5 days in ‘Burana Diamond’ compared with the control. ‘Artemis’ did not respond to night break treatment by flower bud formation, but a leaf bud appeared instead. Night break treatment resulted in greater effect on leaf bud formation than extending day length. A similar phenomenon was also observed in the nursery during the long day (summer) season. The experimental results suggested that night break treatment could be a method to control flowering and stabilize productivity.
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