![]() ![]() 2003), Chl a fluorescence and delayed fluorescence (Goltsev et al. 1997), Chl a fluorescence and 820-nm absorbance/transmission (Klughammer and Schreiber 1994 Schansker et al. 2005), Chl a fluorescence and photoacoustic spectroscopy (Buschmann and Koscányi 1989 Snel et al. 2000), dark-adaptation kinetics of OJIP transients (Bukhov et al. 1989 Krall and Edwards 1990), rapid light curves (RLCs) (White and Critchley 1999 Ralph and Gademann 2005), flash-induced fluorescence (Robinson and Crofts 1983 de Wijn and van Gorkom 2001 Bouges-Bocquet 1980, Ioannidis et al. 2004), non-photochemical quenching (NPQ) (Demmig and Winter 1988 Horton and Hague 1988), electron transport rate (ETR) (Genty et al. 1986), JIP test (Strasser and Strasser 1995 Strasser et al. All of these things taken together could turn Chl a fluorescence into a indecipherable signal, but thanks to the development of specific protocols, and by using complementary techniques, the different effects can be separated, turning Chl a fluorescence into a powerful tool for the study of photosynthesis: quenching analysis (Bradbury and Baker 1981 Quick and Horton 1984 Schreiber et al. ![]() 2005) and this effect allows the study of the different redox states (S states) the oxygen-evolving complex of PSII, due to the fact that the lifetime of P680 + is S state dependent. Finally, P680 + is a strong quencher of Chl a fluorescence (Steffen et al. At the same time, Chl a fluorescence is also inversely proportional to changes in dissipative heat emission (a yield effect, i.e., an increase in the yield of heat emission causes a decrease in the yield of fluorescence emission) (e.g., Krause and Weis 1991) and, therefore, Chl a fluorescence can be used as well to monitor regulatory processes affecting the PSII antenna (see, e.g., Question 8). For this reason, the Chl a fluorescence signal can be used as a probe for photosynthetic activity. Although Chl a fluorescence represents only a small fraction of the absorbed energy, its intensity is inversely proportional to the fraction of energy used for photosynthesis (a redox effect) (Duysens and Sweers 1963). Within this spectrum, blue and red light excite chlorophyll more efficiently than green light. The answers draw on knowledge from different Chl a fluorescence analysis domains, yielding in several cases new insights.Ĭhl a fluorescence can be defined as the red to far-red light emitted by photosynthetic tissues/organisms when illuminated by light of approximately 400–700 nm (photosynthetically active radiation or PAR) (McCree 1972). Examples are the effect of connectivity on photochemical quenching, the correction of F V/ F M values for PSI fluorescence, the energy partitioning concept, the interpretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emission spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor applications and the application of neural network approaches for the analysis of fluorescence measurements. Here, additional Chl a fluorescence-related topics are discussed again in a question and answer format. (Photosynth Res 122:121–158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Complementary techniques can help to interpret changes in the Chl a fluorescence kinetics. ![]() Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo.
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