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Action Spectra of Photosynthetic Activities of Chlorella ellipsoidea
Author(s) -
Lundegådh H.
Publication year - 1966
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.1399-3054.1966.tb07041.x
Subject(s) - action spectrum , photosynthesis , photochemistry , chemistry , chlorophyll , carotenoid , monochromatic color , absorption (acoustics) , absorption spectroscopy , spectral line , analytical chemistry (journal) , physics , optics , food science , biochemistry , organic chemistry , chromatography , astronomy
1) Suspensions of Chlorella show an even stronger light scattering than suspensions of chloroplasts of spinach. The bands of absorption are thus broadened and, at higher concentrations, moved to lower wave‐lengths. The intensity of the photosynthesis closely follows the curves of light scattering, a fact partly explaining the high efficiency of green light. Calculated per unit thermoelectrically measured incident energy the action spectrum shows bands at 660–670 nm and c. 500 nm and a comparatively high level of the whole region 500–560 nm. 2) Flash experiments show the existence of a steady state carotene/xanthophyll that is moved to reduction (c/x > 1) in blue and green light and to oxidation (c/x < 1) in red light. All experiments point to the existence of two light reactions, the first one involving excitation of carotenoids, with ferredoxin‐TPN as acceptor, the second one involving excitation of chlorophyll, with the cytochrome system of the chloroplasts acting as donors of electrons and thus completing an energy converting circulation between pigments and enzyme systems. 3) The operation of combined light reactions appears also from experiments with simultaneous or succedaneous illumination with monochromatic light of different wave‐lengths. Some effects may be explained from separate excitations of carotenoids and chlorophylls, others may depend on still unknown photic reactions. 4) The action spectrum in ultrared shows a positive band at c. 900 nm but no or only very small effects in the region 950–1400 nm. Ultrared radiation has on the other hand an enhancing effect on the light excitation in the visible spectrum. A combination of infrared and visible radiation shows a roughly linear relation between incident energy and photosynthetic effect. 5) All experiments were performed in the region of linear relation between intensity of incident light and O 2 ‐production. Induced effects of combined monochromatic regions show a very rapid initial change in the steady states that in one or two minutes simmers down to a balanced state of continued photosynthesis. No change was observed in the total quantity of the pigments.