title: C4 plants use fluctuating light less efficiently than do C3 plants: a study of growth, photosynthesis and carbon isotope discrimination.
abstract: Plants in the field are commonly exposed to fluctuating light intensity, caused by variable cloud cover, self-shading of leaves in the canopy and/or leaf movement due to turbulence. In contrast to C3 plant species, only little is known about the effects of dynamic light (DL) on photosynthesis and growth in C4 plants. Two C4 and two C3 monocot and eudicot species were grown under steady light or DL conditions with equal sum of daily incident photon flux. We measured leaf gas exchange, plant growth and dry matter carbon isotope discrimination to infer CO2 bundle sheath leakiness in C4 plants. The growth of all species was reduced by DL, despite only small changes in steady-state gas exchange characteristics, and this effect was more pronounced in C4 than C3 species due to lower assimilation at light transitions. This was partially attributed to increased bundle sheath leakiness in C4 plants under the simulated lightfleck conditions. We hypothesize that DL leads to imbalances in the coordination of C4 and C3 cycles and increasing leakiness, thereby decreasing the quantum efficiency of photosynthesis. In addition to their other constraints, the inability of C4 plants to efficiently utilize fluctuating light likely contributes to their absence in such environments as forest understoreys.
authors.affiliation: Global Change Research Centre, Academy of Sciences of the Czech Republic, Brno, Czech Republic.|The University of South Bohemia, Faculty of Science, CZ-370 05, České Budějovice, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Kubásek
authors.affiliation: Global Change Research Centre, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Otmar
authors.initials: O
authors.lastname: Urban
authors.affiliation: The University of South Bohemia, Faculty of Science, CZ-370 05, České Budějovice, Czech Republic.|Biology Centre, Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, CZ-370 05, České Budějovice, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Šantrůček
mesh_terms: D027703:Amaranthaceae / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D008027:Light; D017785:Photons; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D018526:Plant Transpiration; D006109:Poaceae / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide