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RELATIVE IMPORTANCE OF BLUE LIGHT AND LIGHT ABSORBED BY PHYTOCHROME IN GROWTH OF MUSTARD (Sinapis alba L.) SEEDLINGS *
Author(s) -
DrummHerrel Helga,
Mohr Hans
Publication year - 1985
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.1751-1097.1985.tb01640.x
Subject(s) - sinapis , hypocotyl , phytochrome , seedling , phototropism , photomorphogenesis , blue light , botany , far red , biology , white mustard , sowing , red light , horticulture , biophysics , arabidopsis , physics , brassica , mutant , optics , biochemistry , gene
— Hypocotyl straight growth in mustard ( Sinapis alba L.) responds very strongly and in precisely the same way to low fluence rate red (RL) and white light (WL). The effect of weak light can be attributed fully to light absorption by phytochrome. Only with increasing fluence rate an effect of blue light (BL) comes into play which cannot be explained by the action of phytochrome. However, this specific action of BL can be demonstrated in hypocotyl growth of mustard seedlings only up to 5 days after sowing (25°C). With older seedlings control of hypocotyl growth seems to be exerted exclusively via phytochrome. Regarding the far‐red light dependent “high irradiance reaction” (FR‐HIR) it was found that it plays a dominant role in growth of mustard only during a relatively short period. It tends to disappear in favor of a RL‐HIR between 3 and 4 days after sowing. It is concluded that the seedling exhibits a largely endogenous temporal pattern of responsiveness to light. Phototropism of the mustard seedling can be elicited by low fluence rates (< 1 mW m −2 ) of unilateral BL. This same light has no effect on straight growth. It is concluded that BL‐dependent phototropic growth response of a hypocotyl and the effect of BL on longitudinal growth of the hypocotyl are unrelated phenomena.