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Photon requirement for growth of the diatom Phaeodactylum tricornutum Bohlin (Bacillariophyceae)
Author(s) -
OSBORNE B. A.,
GEIDER R. J.
Publication year - 1987
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11602093
Subject(s) - phaeodactylum tricornutum , photosynthesis , diatom , carbon fixation , photon flux , flux (metallurgy) , oxygen , biology , photosynthetic efficiency , botany , photon , physics , chemistry , optics , organic chemistry , quantum mechanics
Abstract Photon requirements for growth (φ g −1 ) of the diatom Phaeodactylum tricornutum were determined under nutrient‐sufficient conditions at two photon flux densities corresponding to light limited and near‐saturating conditions for growth. The value of φ g −1 based on assimilated carbon was light‐dependent and varied from 8.8 to 14.0 mol photon mol C −1 with the minimum value at the lowest photon flux density. These results are lower than might be predicted for microalgal growth based on the Z scheme of photosynthesis. Conversion of these values for carbon fixation to estimates based on oxygen evolution is problematical due to uncertainty over the appropriate assimilatory quotient (Q a = mol O 2 mol C −1 ). Minimum values based on oxygen evolution rates ranged from 6.2 to 7.6 mol photon mol O 2 −1 using a Q a of 1.41 mol O 2 mol C −1 obtained by Myers (1980). These estimates are similar to our previous measurements for photosynthesis and indicate a high efficiency for light energy transforming reactions during growth. The values of (φ g −1 obtained in this work indicate a number of inadequacies in our understanding of the energetics of microalgal growth and are inconsistent with our present knowledge of photosynthetic energy coupling in plant cells.