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Updated: Jul 26, 2026
14:20
Absolute Quantum Yield Measurement of Powder Samples
Published on: May 12, 2012
Loss of quantum yield in extremely low light
Miko U F Kirschbaum1, Christian Ohlemacher, Manfred Küppers
1CSIRO Forestry and Forest Products, PO Box E4008, ACT 2604 Kingston, Australia. miko.kirschbaum@csiro.au
Planta
|January 15, 2004
Summary
Photosynthetic quantum yield in C3 plants decreases after darkness but recovers quickly with low light. This reduction is only significant in very dense shade, having minimal impact on overall carbon gain for most plants.
Area of Science:
- Plant Physiology
- Photosynthesis Research
Background:
- Traditionally, photosynthetic quantum yield in C3 plants was considered constant under unstressed conditions.
- Recent studies suggest darkness can temporarily reduce quantum yield.
Purpose of the Study:
- To determine the light conditions under which quantum yield reduction occurs after darkness.
- To quantify the impact of darkness and subsequent light exposure on quantum yield in C3 plants.
Main Methods:
- Experiments were conducted on Coleus blumei hybrid leaves grown in partial shade.
- Quantum yield was measured after periods of darkness and varying light intensities.
Main Results:
- Quantum yield decreased by approximately 60% after complete darkness.
- Light levels as low as 5 micromol quanta m(-2) s(-1) restored 85% of maximum quantum yield.
- Recovery of quantum yield followed an exponential pattern with a time constant of 130 s.
Conclusions:
- Darkness-induced reduction in quantum yield is significant but rapidly reversible with low light.
- This reduction is quantitatively important only in extremely dense understory conditions (light < 5 micromol quanta m(-2) s(-1)).
- The overall impact on total carbon gain for most C3 plants is marginal.
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