2.5 Assessment of photosystem II parameters
PSII efficiency was assessed using the Chl a fluorescence
induction (FI) technique. We used the multifunctional plant efficiency
analyser (M-PEA; Hansatech, King Lynn, Norfolk, UK) for the evaluation
of PSII parameters as described in details by Essemine et al. (2017).
Plants were dark-adapted for at least one hour at 25°C before
measurements. Then, healthy and fully expanded leaves were exposed to
saturating orange-red (625 nm) actinic light (5,000 µmol
m-2 s-1) provided by the LED for 1
second. The ratio of variable fluorescence level Fv(Fm-F0) to maximal fluorescence level
Fm (Fv/Fm) was used to
evaluate the maximum efficiency of PSII. Fm (P-level)
represents the maximum yield of Chl a fluorescence and
F0 (O-level) is the minimum Chl a fluorescence
(the intensity of Chl a fluorescence of dark-adapted sample with
a measuring beam of negligible actinic light intensity).
Fv/F0 parameter represents the
functional reaction center of PSII. All the parameters listed in the
Table S1 were calculated from the original OJIP curves according to the
so-called JIP-test (Strasser et al., 2004)