Abstract
This study was carried out to clarify the effects of temperature during different developmental stages on the initiation and development of flower buds of Leucojum aestivum and L. autumnale which bloom in March and August, respectively.
1. Flower initiation occurred at any temperature from 10°to 30°C, but the optimum temperature for flower initiation and further differentiation of floral organs was 20°-25°C in both species.
2. In L. autumnale, development of flower buds from carpel formation stage to flowering progressed more rapidly at 20°-25°C than it did at 30°C, and flower buds ceased developing and blasted at 10°-15°C.
3. In L. aestivum, further development of flower buds after carpel formation stage was inhibited when plants were placed at or above 20°C. Shifting the plants to 10°-15°C resulted in anthesis. However, plants had to be kept at 10°-15°C up to anthesis, otherwise they failed to flower. This result indicates that a temperature range of 10°+15°C is indispensable for maturation of flower buds and elongation of scapes.
4. From these results, it was proved that the difference in flowering time between L. autumnale and L. aestivum under natural conditions is ascribed to difference in response of flower buds to the temperature after the formation of carpel initials, i.e., flowering occurred rapidly at the temperature range of 20°-25°C in L. autumnale, whereas an exposure to temperatures ranging between 10°-15°C was required for flowering in L. aestivum.
