Photosynthetic induction strongly affects the light compensation point of net photosynthesis and coincidentally the apparent quantum yield
- H. TimmAffiliated withInstitut für Botanik und Botanischer Garten, Universität Hohenheim, Garbenstrasse 30, 70593 Stuttgart, Germany
- , J. StegemannAffiliated withInstitut für Botanik und Botanischer Garten, Universität Hohenheim, Garbenstrasse 30, 70593 Stuttgart, Germany
- , M. KüppersAffiliated withInstitut für Botanik und Botanischer Garten, Universität Hohenheim, Garbenstrasse 30, 70593 Stuttgart, Germany
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The CO2 assimilation of tree saplings in a Costa Rican premontane forest characterized by highly dynamic light was measured using a rapidly responding system for the analysis of leaf gas exchange. Experiments were carried out on light compensation point and apparent (incident) quantum yield of dynamic photosynthesis. Because of the large variability in photosynthetic induction by light, CO2 assimilation cannot be predicted using steady-state response curves.
Under fluctuating light conditions the light compensation point and, coincidentally, the apparent incident quantum yield are observed to be highly variable and strongly affected by photosynthetic induction. As a consequence, actual light compensation points of net photosynthesis are considerably higher (up to 250%) and apparent quantum yields are considerably lower (by more than 80%) than those obtained in steady state, both in a low light environment typical for the understorey and at a high light regime in open sites. An explanatory model of induction-dependent whole leaf light compensation points and apparent quantum yields is offered on the basis of an assumed constant quantum yield and light compensation point at the chloroplast level.
Most leaves under natural conditions are exposed to highly variable light, either caused by variable cloud cover or by self-shading of leaves in the crown periphery and their movement in turbulence. These effects must not be neglected when considering ecological consequences of low light on shade tolerance of species or when considering carbon balances; they are discussed in relation to their significant effects on carbon gain at a whole plant level.
- Photosynthetic induction strongly affects the light compensation point of net photosynthesis and coincidentally the apparent quantum yield
Volume 16, Issue 1 , pp 47-62
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- Apparent (incident) quantum yield Dynamic CO2 assimilation Dynamic photosynthesis model Photosynthetic induction Light compensation point of net photosynthesis