PMID: 5904590Jan 1, 1966

Monochromatic light saturation curves for photosynthesis in Chlorella

Plant Physiology
J M Pickett, J Myers

Abstract

We used a small oxygen electrode and a grating monochromator of 10 mmu half-band width to determine light-saturation curves of photosynthesis for films of Chlorella pyrenoidosa no more than 1 cell thick. All curves were referenced to the lightsaturated rate observed in 5 mw/cm(2) of 680 mmu. To a close approximation (+/- 2%) the light-saturated rate was independent of wavelength over the region in which light intensity was sufficient to make the test (450-705 mmu). At wavelengths of high absorption we obtained intensities sufficient to cause photoinhibition. As a measure of photoinhibition we used the breakpoint, the lowest intensity at which rate of photosynthesis decreased with time. In general, the saturated rate was slightly lower and the estimated breakpoint was considerably lower at wavelengths of high absorption. Maximum rate of absorption of quanta at the breakpoint was highest in the far-red (>/= 700 mmu), lower and relatively constant in the near-red (630-680 mmu), and lowest in the blue. At 435 and 450 mmu the breakpoint occurred below saturation. We attribute small deviations in maximum rate of photosynthesis to effects of photoinhibition. Independence of wavelength observed for the light-saturated rate is consisten...Continue Reading

Citations

Jan 1, 1967·The Journal of General Physiology·G H Schmid, H Gaffron
Dec 1, 1968·Journal of Phycology·J E Mann, J Myers
Apr 1, 1972·Applied Optics·R C Smith, W H Wilson
Nov 1, 1984·Biotechnology and Bioengineering·A ProkopS A Ahmed

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