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Spectral Requirements for Flower Initiation in Two Longday Plants, Rape ( Brassica campestris cv. Ceres), and Spring Wheat ( Triticum × aestivum )
Author(s) -
Friend D. J. C.
Publication year - 1968
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1968.tb07348.x
Subject(s) - phytochrome , brassica , action spectrum , biology , horticulture , botany , pigment , red light , chemistry , organic chemistry
Action spectra for the promotion of flowering by long periods of irradiation in the red and far‐red regions of the spectrum have been determined by the use of interference filters. The percentage floral initiation was greatest at 710–720 um for both wheat and rape (about 1 k erg · cm −2 · s −1 ). Lowering the temperature from 35 to 15°C did not shift the most effective wavelength, suggesting that the effect of high levels of radiation at 710 nm was not related to a balance between photoactivation of phytochrome and its destruction. In both wheat and rape, an increase in temperature promoted the flower‐initiating action of broad‐band far‐red and 710 nm radiation more than the action of broadband red or 660 nm radiation. The flower‐promoting effect of broad‐band red and 600 nm radiation was particularly depressed by temperatures above 25°C. It is concluded that the promotion of flowering by long periods of high energy at 710 nm is caused by the activity of a high‐energy pigment, rather than through a special effect of phytochrome.