KOREASCHOLAR

This study was performed to investigate how changing the period of light and dark influences the vegetative growth and the photosynthesis of Doritaenopsis Queen Beer ‘Mantefon’. Clones of Dtps. Queen Beer ‘Mantefon’ at 4-month-old stage were grown in a closed-plant factory system with four different light/dark cycles; 06/06 h, 08/08 h, 10/10 h, and 12/12 h. Temperature and relative humidity were set at 28oC and 80%, respectively, with a photosynthetic photon flux density of 160 ± 10 μmol·m-2·s-1. Repetitive measurements showed that the leaf length and the leaf width were the longest under 12/12 h closely followed by 10/10 h. The fresh weight and the dry weight of leaves and roots were the heaviest at 10/10 h treated samples. Different CO2 uptake patterns were observed from different light/dark cycles. Under 10/10 h and 12/12 h treatments, the CO2 uptake started at early dark period. When the light/dark cycles were shortened to 06/06 h and 08/08 h, the CO2 uptake started at the middle of dark period. Total CO2 uptake amounts were the highest under 12/12 h treatment followed by 10/10 h, 06/06 h, and 08/08 h treatments. Quantitative measurements showed that the vegetative growths under 10/10 h treatment were comparable with that of 12/12 h treatment. These studies indicated that manipulating light/dark can modify the photosynthesis patterns and vegetative growth of Dtps. Queen Beer ‘Mantefon’, resulting in the reduction of the production period.

Introduction
 Materials and Methods
  Plant and growth conditions
  Photoperiod and temperature treatments
  Data collection and statistics
 Results and Discussion
  Effects of light/dark cycle manipulation on CO2uptake patterns
  Effects of light/dark cycle manipulation onvegetative growth
 References

• Hyo Jin Kim(Department of Horticultural Science and Biotechnology, Seoul National University)
• Ju Hui Lee(Department of Horticultural Science and Biotechnology, Seoul National University)
• Hyo Beom Lee(Department of Horticultural Science and Biotechnology, Seoul National University)
• Seong Kwang An(Department of Horticultural Science and Biotechnology, Seoul National University)
• Ki Sun Kim(Department of Horticultural Science and Biotechnology, Seoul National University, Research Institute of Agriculture and Life Sciences, Seoul National University) Corresponding author