Flowering responses under night interruption (NI) condition were determined in Doritaenopsis ‘Fuller’s Sunset ’, ‘Green Beer’, ‘Little Gem Stripes’, and ‘Queen Beer’ during their reproductive stages. Plants were grown under 10/14 h ambient light/dark (control), 10 h ambient light with night interruption (22 : 00-02 : 00 HR) at low light intensity of 3-7 μmol • m−2 • s−1 (LNI) and 10 h ambient light with NI at high light intensity of 120 μmol • m−2 • s−1 (HNI) conditions after flower spike emergence. Time to visible bud and flowering decreased more in the plants grown under HNI than those grown under LNI or control conditions. The number of buds or flowers increased in the plants grown under both LNI and HNI conditions compared to those grown under control condition for all cultivars. The tallest plants at flowering were in the HNI group in ‘Queen Beer’, ‘Green Beer’, and ‘Fuller’s Sunset’, however, the plant height was not significantly different among the treatments in ‘Little Gem Stripes’. NI with low light intensity or high light intensity can be used effectively to promote flower opening, but not with low light intensity at flower development stage. To obtain early flowering with high quality plants using NI treatment during their reproductive stage, high light intensity strategies could be suggested in Doritaenopsis cultivation.

Introduction
 Materials and Methods
  Plant and growth conditions
  NI treatment
  Data collection and analysis
 Results and Discussion
 Acknowledgments
 References

• Yoon Jin Kim(Department of Horticulture, Biotechnology and Landscape Architecture, Seoul Women’s University, Seoul 139-774, Korea, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea)
• Yu Jin Park(Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea)
• Ki Sun Kim(Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea, Department of Horticultural Science and Biotechnology, Seoul National University, Seoul 151-921, Korea) Corresponding author