PSI FluorPen FP 110 Instruction Guide

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5.3.2 NON-PHOTOCHEMICAL QUENCHING (NPQ) PROTOCOLS
The NPQ protocol is used to quantify photochemical and non-photochemical quenching. It should be performed with dark-adapted
samples. The NPQ protocol starts with measurement of minimal level of fluorescence F
0
during a dark period. 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 called the Kautsky effect.
A sequence of saturating flashes is then applied during exposure to 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. This sequence of the protocol is illustrated in Fig.
9.
The FluorPen device comes with three predefined NPQ protocols, NPQ1, NPQ2 and NPQ3. The protocols differ in the duration of the light
exposure and the dark recovery phase, and in the number and interval between pulses. See Table 2:
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
Table 2 NPQ Protocols.
The NPQ protocols include the 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
_Ln, Lss, D, Dn
1
maximum fluorescence
QYmax
2
maximum quantum yield of PSII in dark-adapted state - F
v
/F
m
QY_Ln, Lss, D, Dn
1,3
effective quantum yield of PSII
NPQ_Ln, Lss, D, Dn
1,4
non-photochemical chlorophyll fluorescence quenching
Qp_Ln, Lss, D, Dn
1,5
coefficient of photochemical quenching, an estimate of open PSII reaction centers
1
L - indicates light adapted parameters; D - refers to dark recovery phase after switching of the actinic illumination; n - represents a
sequential number of light phases; ss - steady state
2
Calculated as (F
m
– F
0
) / F
m
3
Calculated as (F
m
_Ln – F
t
_Ln) / F
m
_Ln or of corresponding steady state or dark recovery parameters
4
Calculated as (F
m
– F
m
_Ln) / F
m
_Ln or of corresponding ss, Dn or Dss parameters
5
Calculated as (F
m
_Ln – F
t
_Ln) / (F
m
_Ln – F
0
_Ln) or of corresponding ss, Dn or Dss parameters

PSI FluorPen FP 110 Specifications

General

Brand	PSI
Model	FluorPen FP 110
Category	Measuring Instruments
Language	English