Pulsed amplitude modulation

In recent years, pulse amplitude modulated (PAM) chlorophyll fluorescence associated with the photosystem II (PS II) has become a useful tool for evaluation of photosynthesis [86-90]. In fact, chlorophyll fluorescence can be an... 

S. Beer, B. Vilenkin A. Weil, M Vete, L. Susel, A. Eshel (1998). Measuring photosynthetic rates in seagrasses by pulse amplitude modulated (PAM) fluorometry. Mar. Ecol. Prog. Ser., 174, 293-300. 

P.J. Ralph, R. Gademann, W.C. Dennison (1998). In situ seagrass photosynthesis measured using a submersible, pulse-amplitude modulated fluorometer. Mar. Biol, 132, 367-373. 

D.-P. Hader, H. Herrmann, R. Santas (1996). Effects of solar radiation and solar radiation deprived of UV-B and total UV on photosynthetic oxygen production and pulse amplitude modulated fluorescence in the brown alga Padina pavonia. FEMS Microbiol. Ecol., 19, 53-61. 

PAM/FM pulse amplitude modulation/frequency PG plastic-concrete... 

Chlorophyll fluorescence was recorded by a pulse amplitude modulated (PAM) fluorometer (Walz). 

Figure 2 represents a schematic drawing of the combined Chi fluorescence and PAS instrumental setup. The fluorescence of the plant leaf was determined with a Pulse Amplitude Modulation fluorometer (PAM chlorophyll fluorometer, Walz, Effel-trich, Germany) as described in (6). Excitation and emission light passed through the fiberoptics, consisting of four separate bundles, which merge... 

Chlorophyll fluorescence was measured using a pulse amplitude modulation fluorometer (PAM, Heinz Walz, Effeltrich, FRG) as described by [7]. The methods and definitions from [7] were employed to calculate the quenching components qQ, qNP and qTot, which are respectively photochemical quenching, non-photochemical quenching and total quenching of variable fluorescence, all corrected for Fo-quenching (qFo). At each light intensity level, the leaf disc was allowed to achieve steady state of 02-production and fluorescence and then Fs, Fv and Fo were measured. 

A infrared gas analyzer and an open steady state system. Chi fluorescence was measured at 20 C using a pulse amplitude modulated fluorometer (4). Fluorescence measurements were made after leaves used in the gas exchange studies were dark adapted for 90 min. Changes in the ratio of the maximum variable fluorescence (Fvm) to initial fluorescence (Fo) were evaluated in terms of increases in Fo/chl resulting from uncoupling of PSII antenna (5) and decreases in Fvm/chl due to photoinhibition (6). 

Chlorophyll fluorescence was measured by a pulse amplitude modulation fluorimeter Hansatech. 

FIGURE 12.49 llustration of practical sampling of a signal and pulse modulation techniques (a) pulse sampling function, (b) signal to be sampled, (c) natural sampling, (d) flat top sampling or pulse-amplitude modulation, (e) pulse-width modulation, (f) pulse-position modulation. 

Chi a fluorescence is a property exhibited by all photosynthetic organisms due to the essential role of chlorophyll in the structure and function of the photosynthetic apparatus. Typically less than 3% of the absorbed light is ever re-emitted as chlorophyll fluorescence and, at room temperature, the latter primarily emanates from PSII (Krause and Jahns, 2003). Quantification of chlorophyll a fluorescence induction has proven to be an extremely useful tool to assess the structure and ftmction of PSII and the overall process of photosynthesis (Krause and Weis, 1991 Krause and Jahns, 2003). Since reduced Qb is in equilibrium with the reduced PQ pool, the relative reduction state of the PQ pool, also called excitation pressure, can be estimated in vivo as the relative reduction state of Qa, that is [Qa ] / ([Qa] + [Qa ]), which can be conveniently measured in vivo as 1-qP using pulse amplitude modulated... 

Krause GH, and Jahns P. Pulse amplitude modulated chlorophyll fluorometry and its application in plant science. Advances in Photosynthesis and Respiration. Light Harvesting Antennas in Photosynthesis (Green BR, Parson WW eds). 2003 13 373-399. Kluwer Academic Publishers, Dordrecht. 

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