Abstract
Vegetative and flower bud formations in Camellia wabisuke 'Tosauraku' exposed to 15°, 20°, and 25°C and photoperiod of 10 and 16 hr were compared with those of plants exposed to ambient temperatures in a glasshouse and natural daylength (control) from 1 April 1990 to 1 April 1991.
1. The vegetative bud developed earlier at 20°C in the initial stage of formation, but growth in longitudinal diameter was faster at 15°C after August. The sizes of vegetative buds at 25°C and natural temperature were half of those at 15°C on 1 November.
2. From 15° to 25°C, the number of outer scales increased with the increasing temperatures, while the number of leaf primordia decreased with the increasing temperatures. The number of inner-scales was not affected by temperature.
3. Terminal and axillary buds of plants kept at 15°C sprouted after 1 November (after a 7-month treatment) ; those kept at 20°C began to sprout after 1 February (after 10-month- treatment). No plant kept at 25°C sprouted by 1 April 1991 (after one-year-treatment).
4. The rate of formation of flower buds at 25°C was hastened by mid-June (after 45-day- treatment), but the development of flower buds at 20°C was the fastest after August; it was slowest at 15°C and under natural conditions.
5. Flower buds at 20° and 15°C began blooming in mid-October (after 6.5-month-treatment) and in early November (after 7-month-treatment), respectively, but those on plants kept at 25°C became necrotic during November and December.
6. The number of bracts and sepals constituting a flower bud was not affected by temperature. The number of petals per flower at 15°C was two more than that at 20° and 25°C.
7. The number of outer scales and inner-scales in vegetative buds was not affected by photoperiod, but the number of leaf primordia was somewhat larger under the short-day. Moreover, the time of flower bud initiation was unaffected by photoperiod, but plants under the short-day bloomed 20 days earlier than did those under the long-day.
