PSI FluorPen FP 110 User Manual

© PSI (Photon Systems Instruments), spol. s r. o.
21
Formulas Derived From:
R.J. Strasser, A. Srivastava and M. Tsimilli-Michael (2000): The fluorescence transient as a tool to characterize and screen
photosynthetic samples. In: Probing Photosynthesis: Mechanism, Regulation and Adaptation (M. Yunus, U. Pathre and P.
Mohanty, eds.), Taylor and Francis, UK, Chapter 25, pp 445-483.
7.3.2 NON-PHOTOCHEMICAL QUENCHING (NPQ) PROTOCOL
The NPQ protocol is the most typically used measuring approach to quantify photochemical and non-photochemical
quenching. The measurement should be performed with a dark-adapted sample. Thereby, it may not be appropriate
under field conditions.
The NPQ protocol starts by giving a measuring light to acquire minimal level of fluorescence F
0
. A short saturating flash of
light is then applied to reduce the plastoquinone pool and measure maximum fluorescence in the dark-adapted state, F
m
.
After a short dark relaxation, the sample is exposed to actinic irradiance for tens to hundreds of seconds to elicit a
transient of the Kautsky effect. Moreover, a sequence of saturating flashes is applied on top of the actinic light to probe
the non-photochemical quenching NPQ and effective quantum yield of photosynthesis QY in light adapted state. After
exposure to continuous illumination, the relaxation of non-photochemical quenching is determined by means of
saturating pulses applied in dark (Fig. 8).
Three NPQ protocols, NPQ1, NPQ2 and NPQ3 are predefined. The protocols differ in the duration of the light exposure
and the dark recovery phase, in the number and interval between pulses. See table below:
Phase
Duration
# of pulses
1st pulse
Pulse interval
NPQ1
Light
60 s
5
7 s
12 s
Dark recovery
88 s
3
11 s
26 s
NPQ2
Light
200 s
10
10 s
20 s
Dark recovery
390 s
7
20 s
60 s
NPQ3
Light
200 s
10
11 s
21 s
Dark recovery
60 s
2
20 s
21 s
Tab. 2 NPQ Protocols.
The protocol includes following measured and calculated parameters:
Abbreviation
Explanation
F
0
minimum fluorescence in dark-adapted state
F
m
maximum fluorescence in dark-adapted state, measured during the first
saturation flash after dark adaptation
F
p
fluorescence in the peak of fast Kautsky induction
F
m
_L, Lss, D, Dss
1
maximum fluorescence
QYmax
2
maximum quantum yield of PSII in dark-adapted state - F
v
/F
m
QY_L, Lss, D, Dss
1,3
effective quantum yield of PSII
NPQ_L, Lss, D, Dss
1,4
non-photochemical chlorophyll fluorescence quenching
Qp_L, Lss, D, Dss
1,5
coefficient of photochemical quenching, an estimate of open PSII reaction centers

PSI FluorPen FP 110 Specifications

General

Brand	PSI
Model	FluorPen FP 110
Category	Measuring Instruments
Language	English