2.3 Chlorophyll fluorescence parameters
Chlorophyll fluorescence parameters were determined using a portable
fluorometer (OSF1, ADC Bioscientific Ltd.,UK) after adapting the leaves
(youngest fully expanded leaf in all treatments) to dark for 10 minutes.
Initial (F0), maximum (Fm), and variable
(Fv = Fm-F0)
fluorescence values were measured by the device. Other parameters were
calculated using the following formulas (Rühle et al., 2014).
Maximal quantum yield of PSI = Fv/Fm
ΦII (effective quantum yield of
PSII)=F’v/F’m
NPQ= 1 - [(F’m -
F’0)/(Fm - F0)]= 1 -
(F’v/Fv)
ETR= ΦII (PAR \(\times\) 0.84 \(\times\) 0.5)
q0= (F0 -
F’0)/F0= 1 -
(F’0/F0)
qP= (F’m -
Fs)/(F’m - F’0)
qA= (Fm -
F’0)/Fm= 1 -
(F’0/Fm)
Rfd= (Fm - Fs)/Fs=
(Fm/Fs) - 1
SV0= (F0-
F’0)/F’0=
(F0/F’0) - 1