PHYA is the only gene that encodes a Type I phytochrome and predominantly perceives far-red light.

Phytochrome B predominantly perceives red light

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#Id: 9818

#XL - R Botany

VLFRs are non-photoreversible.

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#Id: 9819

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Arabidopsis seeds can be induced to germinate with red light in the range of 0.001 to 0.1 μmol m–2 at very-low-fluence responses (VLFRs).

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#Id: 9820

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LFRs is found at red region (660 nm) and (720 nm) includes processes such as the promotion of lettuce seed germination, inhibition of hypocotyl elongation, and regulation of leaf movements.

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#Id: 9821

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A brief pulse of red light will induce a response, provided that the light is sufficiently bright, and conversely, very dim light will work if the irradiation time is long enough. 

This reciprocal relationship between fluence rate and time is known as the law of reciprocity

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#Id: 9822

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VLFRs and LFRs both obey the law of reciprocity

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#Id: 9823

#XL - R Botany

HIRs require prolonged or continuous exposure to light of relatively high irradiance, and the response is proportional to the irradiance