HANSATECH FMS1, Manual

Page: 63 / 86

63 Section 2: Software Installation, System Operation, Data Handling
© 2017 Hansatech Instruments Ltd
Fig. 2-37 . Fluorescence trace observed after Fv/Fm , adaptation to actinic light and
f
PSII measurement (boxed area).
1. Values of PAR and temperature are logged from the leaf-clip (these will be zero if the clip is not
connected),
2. The steady state fluorescence value (Fs) is determined by averaging the fluorescence signal
under the ambient light,
3. A saturation pulse, defined by the intensity and duration values in the “Pulse” edit boxes, is
applied and Fm’ stored as the average of the highest consecutive values. At the end of the
function the following measured and calculated parameters are presented in the “Parameters
Window”:
Parameter Measurement Units Derivation
PAR Incident
photosynthetically
active radiation
µmolm
-2
s
-1
Temp Incident
photosynthetically
active radiation
°C
Fs Steady state
fluorescence yield
Bits
Fm' light-adapted
fluorescence maximum
Bits
f
PSII
quantum efficiency of
PSII
No Units = (Fm’-Fs) / Fm’
(Genty et al. 1989)
qp photochemical
quenching co-efficient
No Units (Fm’-Fs) / (Fm’- Fo)
qNP Non-photochemical
quenching co-efficient
No Units = (Fm-Fm’) / (Fm-Fo)
NPQ Alternative definition of
non-photochemical
quenching
No Units = (Fm-Fm’) / Fm’
ETR Electron transport rate No Units
=PAR * 0.5 *
f
PSII *
0.84
It is important to note that in some of the derived parameters such as the quenching coefficients
reference data that is not encompassed within the fPSII measurement function. As a result it is
possible to make perfectly valid measurements of fPSII (which does not require referencing to data
outside of the measurement function) whilst calculating invalid measurements of quenching
coefficients (which require referencing to a dark-adapted measurement of Fo and Fm). Error
trapping routines have been built into FMS which operate according to the following rules: