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DEPENDENCE OF P fr /P tot ‐RATIOS ON LIGHT QUALITY and LIGHT QUANTITY
Author(s) -
Jabben M.,
Beggs C.,
Schaufer E.
Publication year - 1982
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1982.tb02634.x
Subject(s) - phytochrome , etiolation , fluence , white light , irradiation , blue light , chemistry , optics , physics , botany , biology , red light , biochemistry , nuclear physics , enzyme
— Not only the spectral distribution of the light source determines the relative proportion of phytochrome in the P fr (P r ) form, the P fr /P tot ‐ratio also depends strongly on the fluence rate of the irradiation. This dependence has been observed in the cotyledons of etiolated mustard seedlings for blue light of fluence rates below 20 Wm ‐2 . It has also been observed for white light and seems to be a characteristic of the phytochrome system resulting from the involvement of phytochrome thermal reactions as well as P r P fr photoconversions. The fluence rate dependence of P fr /P tot ‐ratios can be used to analyze the characteristic transformations of the phytochrome system. Phototransformations together with a fast thermal transformation (τ ½ ⋍ 3min) are consistent with the results obtained for blue and white light.