Time scales, over which photosynthesis is very efficient even at high photon fluxes: The case of unicellular algae
by Prof. Yair Zarmi
Department of Solar Energy and Environmental Physics, Ben-Gurion University of The Negev
at Biological and soft-matter physics
Thu, 06 Jan 2022, 12:10
ZOOM only - Meeting ID: 857 5598 3057 Passcode: 345123
While photon exploitation by the photosynthetic apparatus is highly efficient under continuous irradiation at low photon fluxes (lower than 10-15% of a full sun), the efficiency drops consistently as the flux grows; roughly proportional to the inverse of the flux at high fluxes. This observation has been often documented in the case of unicellular algae.
The simple interpretation is that there is a “bottleneck” time scale in the process of energy delivery within the photosynthetic process, such that if photons arrive too rapidly (high photon flux), the system is incapable of exploiting all of them and most of the photons are wasted (about 80% of the photons under a full sun).
It will be argued that if one takes into account:
1) The “bottleneck” time scale;
2) The energy storage capacity of the photosynthetic apparatus;
3) The stochastic nature of photon arrival times,
then photon exploitation by the photosynthetic system under a judiciously selected pulsed-light regime can be much more efficient then under continuous irradiation. Data (not a lot of) that show an increase of efficiency by a factor of 3-10 in photon exploitation efficiency in the case of unicellular algae exposed to pulsed light are explained by this approach.
There are many still unanswered questions of a fundamental nature, some of which will be reviewed.
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Created on 16-12-2021 by Granek, Rony (rgranek)
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