BRAINCAKESignal Detection
Flowering in long day and short day plants is controlled by photoperiod, but which part of the plant detects it? Experiments in the 1930s showed that the leaves detect the light signal, not the shoot tip where the flowers form.
If a short day plant is kept in long days but a single leaf is covered so that it receives short days, the plant still flowers. If all the leaves are removed, the plant does not respond to day length at all. So the stimulus is perceived in the leaf and must then travel to the shoot apex.
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Key terms in this lesson
- phytochrome
- A blue-green plant pigment existing in two interconvertible forms sensitive to red and far-red light, controlling responses such as flowering and germination.
More in Chemical Control
- Photoperiodism
- Long Day Plants
- Short Day Plants
- Day Neutral Plants
- Discovery
- Photomorphogenesis
- Germination and Photomorphogenesis
- Phytochromes, Photomorphogenesis and Tropisms
All 30 lessons in Chemical Control · All Edexcel A-level Biology topics