To make clear the effect of age of flower bud at the start of precooling on the time of flowering and the quality of cut flower, tulip bulbs of a cultivar, "Trance" were storaged for various intervals at 0℃ and 22℃ before precooling.
1 ) As the storage at 22℃ was prolonged, the age of flower bud was more progressive and the nose became longer at the start of precooling. A regression equation of Y=1.16X-0.53 (r=0.98***) was obtained between the nose length (Y) and the storage period (X). The floral organ did not completely develop in the tulip bulbs storaged at 22℃ for 4 weeks or less.
2 ) The weight of nose at planting increased with the age of the nose. The nose became longest when a bulb was storaged at 22℃ for 6 weeks.
3 ) Younger bulbs storaged at 22℃ for 2 or 4 weeks required the least days for flowering under forcing, followed by older bulbs storaged for 9 weeks.
4 ) The quality of cut flower was satisfactory for marketing when bulbs were storaged at 22℃ for longer than 5 weeks and the nose length exceeded 5 mm at the start of precooling. Even if the nose was shorter than 5 mm, bulbs with completely developed floral organ were acceptable for the cut flower production under forcing.