Semi-forcing culture of refrigerated tulip bulbs using the Adachi frame method

Tulips used to be widely known as the 'flower of Adachi'. During the peak season, the area produced six million cut flowers annually, which is the largest amount produced in Japan (Kamoshita 1957, Tokyo Metropolitan Government Agriculture and Forestry Department 1968). This large-scale production of cut tulip flowers was made possible mainly by the 'Adachi frame', which was invented by Kinzo Kamoshita who was a resident of Adachi ward of Tokyo (Tokyo Flower Growers' Association 1968). In 2015, a well-preserved Adachi frame was found in the shed of a 92-year-old farmer. This discovery got me interested in how the Adachi frame could be applied to the production of tulips at present. Therefore, I conducted an experiment by making a replica of the Adachi frame for use in future tulip production in Tokyo. The experiment was conducted on an experimental field at the Edogawa Branch of the Tokyo Metropolitan Agriculture and Forestry Research Center. To test the Adachi frame, I prepared one single-layered and one double-layered plastic greenhouse next to the Adachi frame which faced south, and conducted semi-forcing cultures of cut tulip flowers from refrigerated bulbs without providing heat. 1. The average temperature during the cultivation period was 10.1℃ in the Adachi frame, 9.8℃ in the single-layered greenhouse and 11.9℃ in the double-layered greenhouse, which is slightly low but acceptable for the production of cut flowers. 2. The cut tulip flowers that were produced in the Adachi frame were sturdy, large in height, with excellent flower shape, while the flowers produced in the single-layered greenhouse had a compact flower shape with dark grassy leaves. The double-layered greenhouse was hotter and produced unevenly shaped flowers. 3. The Adachi frame requires a relatively heavy manual ventilation work as the glass door is about 10 kg. Automatic ventilation controllers for greenhouses reduce the labor required for temperature control. As material costs of the Adachi frame are relatively low, this method is well suited for use in greenhouses in Tokyo. 4. The Orange Queen of the Darwin Hybrid family produced flower heads with a circumference of approximately 11 cm. When the bulbs were stored at 20℃ for 43 days, and later at 5℃ for 63 days, the cut tulip flowers could be harvested in the total accumulated room temperature of 500 to 600℃ from the planting and 530 to 620℃ in the total ground temperature. 5. The Orange Queen is a beautiful tulip with bright orange-colored flower heads. The cut flowers are considered to have excellent length and weight.