phytochrome

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phytochrome A photoreversible pigment, which occurs in every major taxonomic group of plants. It exists in 2 interchangeable forms with respect to absorption, a red and a far-red form. This phenomenon is utilized in plants as a switch mechanism, linked to environmental light signals, to control many activities. These include flowering, germination, vegetative growth, circadian rhythms, and many more physiological activities.

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