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Effect of back reactions in the S-cycle on photosynthesis in very weak light

  • Lars Olof Björn
Publishing year: 1995
Language: English
Pages: 203-206
Publication/Series: Photosynthesis Research
Volume: 46
Issue: 1-2
Document type: Journal article
Publisher: Springer

Abstract english

Photosynthesis in light which is so weak that excitation rates are comparable to the decay rates of S-states is modelled. It is found that oxygen evolution rate varies in a non-linear way with Photosystem II excitation rate in this region, but asymptotically approaches a linear relationship (with a slope of one oxygen molecule per four excitations) as excitation rate increases. The asymptote gives an intercept (zero oxygen evolution rate) on the excitation rate axis. The question is raised, whether this model is compatible with photoautotrophy in a red alga found at 268 m depth and able to carry out photosynthesis in extremely weak light. It is found that no unorthodox mechanisms for the S-cycle in this alga have to be assumed to explain its performance.


  • Biological Sciences


  • ISSN: 0166-8595
Lars Olof Björn
E-mail: lars_olof [dot] bjorn [at] biol [dot] lu [dot] se

Professor emeritus

Molecular Cell Biology

+46 46 222 72 53