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EMERSON ENHANCEMENT EFFECT AND THE REACTIVATION OF PHOTOSYNTHESIS IN PHOSPHATE DEFICIENT LEMNA MINOR *
Author(s) -
Lindeman W.
Publication year - 1973
Publication title -
acta botanica neerlandica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0044-5983
DOI - 10.1111/j.1438-8677.1973.tb00877.x
Subject(s) - photophosphorylation , photosynthesis , photosystem , phosphate , chemistry , photosynthetic efficiency , lemna minor , biophysics , botany , photochemistry , biochemistry , biology , photosystem ii , chloroplast , ecology , gene , aquatic plant , macrophyte
SUMMARY Photosynthetic enhancement, studied in the wavelength pair 650/717 nm, is expressed as and as . The maximum values of enhancement are considered to represent the ratio between the “potential cooperative activities” (PCA) of the two photosystems: Under conditions of P‐deficiency E 650(717) max tends to increase. However, when deficient plants have reactivated their photosynthesis (PS) by P‐uptake, it decreases. This result demonstrates that far red light to a certain degree overcomes the inhibiting effect of P‐deficiency. A tentative explanation is based on the hypothesis that in P‐deficient plants PS operates with the less efficient pseudocyclic photophosphorylation at 650 nm as a 12‐quanta process, whereas with background light of 717 nm a switch takes place to a more efficient PS, operating with cyclic photophosphorylation. PS, making use of the cyclic pathway, is thought to operate in plants with normal P‐content, thus showing the normal high efficiency.