Effects of air temperature and day length on differentiation and development of Stephanotis floribunda Brongn. [Asclepiadaceae] flower buds

Three experiments were conducted to test the effects of air temperature and day length on the differentiation and development of flower buds of Stephanotis floribunda Brongn. 1. Flower bud differentiation was stimulated at 23°/18°C (air temperature, day/night) but inhibited at 33°/28°C. Day length did not seem to have any effect on the course of floral differentiation. 2. Independent of the day length, air temperature of 33°/28°C hastened the development of flower buds. Under normal greenhouse temperature condition (temperature ranged between 18° and 30°C), the development of flower buds and anthesis were obsereved when the night cycle was interrupted by four hours of light. Under short day photoperiod, flower bud development was slow, and no flowering was seen during the experimental period. 3. Besides ambient temperature, internal conditions, such as nutritional status of the plant and maturity of the buds, as well as irradiance during the shoot growth may affect floral initiation and/or development of flower buds.