Gender-specific flowering responses to day length in the dioecious plant Silene latifolia at different temperatures

Silene latifolia Poiret is a reliable model system for studying many of the classical problems in biology because little difference in its physiological response to environmental stimuli has been found between genders. In this experiment, we studied flowering responses to day length in male and female S. latifolia plants grown at different temperatures. The primary objective was to examine whether flowering in male and female plants was differentially influenced by day length and temperature. We hypothesized that temperature would interact with day length in affecting flowering, because both genders have been found to flower in a wide range of day lengths and temperatures. Plants were grown in environmental chambers at a target temperature of 15/10 or 30/25 degrees C (day/night). Day length was increased by half-hour intervals until all plants had flowered. Results showed that S. latifolia is a qualitative long-day plant with a critical day length of 11 h. Flowering accelerated with increasing day length until 16.5 h, when all plants flowered. Males and females differed in relative flowering at different day lengths, but to a greater extent at high than at low temperature. This study demonstrated that flowering of male and female S. latifolia respond differently to day length at different temperatures. A more uniform experimental protocol, especially in controlled environments, is called for to make this model system a more useful tool in biological studies.