3 Chlorophyll Fluorescence
as a Nonintrusive Indicator for Rapid Assessment
of In Vivo Photosynthesis
U. Schreiber, W. Bilger, and C. Neubauer
3.1 Introduction
In the past, ecophysiologically oriented photosynthesis research has been
governed by gas-exchange measurements, mainly involving sophisticated
(and costly) systems for simultaneous detection of CO2 uptake and H 2 0
evaporation (see, e.g., Field et al. 1989). With the help of these methods,
fundamental knowledge on in situ photosynthesis has been gained. Only
recently, progress has been made in the development of alternative practical
methods for nonintrusive assessment of in vivo photosynthesis which have
the potential of not only evaluating overall quantum yield and capacity,
but also allowing insights into the biochemical partial reactions and the
partitioning of excitation energy (see, e.g., Snel and van Kooten 1990). As a
consequence, photosynthesis research at the level of regulatory processes
has been greatly stimulated, leading to important new concepts (see reviews
by Foyer et al. 1990; Demmig-Adams 1990; Melis 1991; Allen 1992). In
particular, chlorophyll fluorescence has evolved as a very useful and informative indicator for photosynthetic electron transport in intact leaves, algae,
and isolated chloroplasts (reviews by Briantais et al. 1986; Renger and
Schreiber 1986; Schreiber and Bilger 1987, 1992; Krause and Weis 1991;
Karukstis 1991).
Chlorophyll fluorescence provides a large signal, which can be measured
at some distance from the sample investigated. Furthermore, highly selective
modulation fluorometers are now available, with which fluorescence yield
can be measured in full sunlight, and which are small and low in power
consumption, such that they are well suited for field measurements. As a
result of intensive research in a number of laboratories, methods are now
available by which the fluorescence information can be quantitatively analyzed and evaluated such that quantum yields and relative electron transport
rates can be obtained. Computerized systems are available which relieve the
user from tedious measuring protocols and calculations of the relevant
parameters derived from fluorescence data. Hence, ecophysiologists are
offered a convenient alternative to gas exchange measurements.
The present chapter is not another general review on chlorophyll fluorescence and the large amount of literature published recently on this topic (for
as a Nonintrusive Indicator for Rapid Assessment
of In Vivo Photosynthesis
U. Schreiber, W. Bilger, and C. Neubauer
3.1 Introduction
In the past, ecophysiologically oriented photosynthesis research has been
governed by gas-exchange measurements, mainly involving sophisticated
(and costly) systems for simultaneous detection of CO2 uptake and H 2 0
evaporation (see, e.g., Field et al. 1989). With the help of these methods,
fundamental knowledge on in situ photosynthesis has been gained. Only
recently, progress has been made in the development of alternative practical
methods for nonintrusive assessment of in vivo photosynthesis which have
the potential of not only evaluating overall quantum yield and capacity,
but also allowing insights into the biochemical partial reactions and the
partitioning of excitation energy (see, e.g., Snel and van Kooten 1990). As a
consequence, photosynthesis research at the level of regulatory processes
has been greatly stimulated, leading to important new concepts (see reviews
by Foyer et al. 1990; Demmig-Adams 1990; Melis 1991; Allen 1992). In
particular, chlorophyll fluorescence has evolved as a very useful and informative indicator for photosynthetic electron transport in intact leaves, algae,
and isolated chloroplasts (reviews by Briantais et al. 1986; Renger and
Schreiber 1986; Schreiber and Bilger 1987, 1992; Krause and Weis 1991;
Karukstis 1991).
Chlorophyll fluorescence provides a large signal, which can be measured
at some distance from the sample investigated. Furthermore, highly selective
modulation fluorometers are now available, with which fluorescence yield
can be measured in full sunlight, and which are small and low in power
consumption, such that they are well suited for field measurements. As a
result of intensive research in a number of laboratories, methods are now
available by which the fluorescence information can be quantitatively analyzed and evaluated such that quantum yields and relative electron transport
rates can be obtained. Computerized systems are available which relieve the
user from tedious measuring protocols and calculations of the relevant
parameters derived from fluorescence data. Hence, ecophysiologists are
offered a convenient alternative to gas exchange measurements.
The present chapter is not another general review on chlorophyll fluorescence and the large amount of literature published recently on this topic (for