. 2020 Jan 17;10:1688. doi: 10.3389/fpls.2019.01688

Table 1.

Formulae and explanation of the technical data of the OJIP curves and the selected JIP-test parameters used in this study^a.

Technical fluorescence parameters
F_t	fluorescence at time t after onset of actinic illumination
F_O ≅ F_20µs	minimal fluorescence, when all PSII RCs are open
F_L ≡ F_150µs	fluorescence intensity at the L-step (150 µs) of OJIP
F_K ≡ F_300µs	fluorescence intensity at the K-step (300 µs) of OJIP
F_J ≡ F_2ms	fluorescence intensity at the J-step (2 ms) of OJIP
F_I ≡ F_30ms	fluorescence intensity at the I-step (30 ms) of OJIP
F_P (= F_M)	maximal recorded fluorescence intensity, at the peak P of OJIP
F_v ≡ F_t – F_O	variable fluorescence at time t
F_V ≡ F_M – F_O	maximal variable fluorescence
t_FM	time (in ms) to reach the maximal fluorescence intensity F_M
V_t ≡ (F_t – F_O)/(F_M – F_O)	relative variable fluorescence at time t
V_K = (F_K – F_O)/(F_M – F_O)	relative variable fluorescence at the K-step
V_J = (F_J – F_O)/(F_M – F_O)	relative variable fluorescence at the J-step
W_t ≡ (F_t – F_O)/(F_J – F_O)	relative variable fluorescence F_v to the amplitude F_J – F_O
W_OK = (F_t – F_O)/(F_K – F_O)	ratio of variable fluorescence F_t – F_O to the amplitude F_K – F_O
W_OJ = (F_t – F_O)/(F_J – F_O)	ratio of variable fluorescence F_t – F_O to the amplitude F_J – F_O
W_OI = (F_t – F_O)/(F_I – F_O)	ratio of variable fluorescence F_t – F_O to the amplitude F_I – F_O
W_IP = (F_t – F_I)/(F_P – F_I)	ratio of variable fluorescence F_t – F_I to the amplitude F_P– F_I
M₀ ≡ 4(F_270μs – F_O)/(F_M – F_O)	approximated initial slope (in ms^–1) of the fluorescence transient normalized on the maximal variable fluorescence F_V
S_m ≡ Area/(F_M – F_O)	normalized total complementary area above the O-J-I-P transient (reflecting multiple-turnover Q_A reduction events)
Ss = V_J/M₀	normalized total complementary area corresponding only to the O-J phase (reflecting single-turnover Q_A reduction events)
Quantum efficiencies or flux ratios
φ_Po = PHI(P₀) = TR₀/ABS = 1– F_O/F_M	maximum quantum yield for primary photochemistry
ψ_Eo = PSI₀ = ET₀/TR₀ = 1–V_J	probability that an electron moves further than $Q_{A}^{-}$
φ_Eo = PHI(E₀) = ET₀/ABS = (1– F_O/F_M) (1–V_J)	quantum yield for electron transport (ET)
φ_Do = PHI(D₀) = 1- φ_Po = F_O/F_M	quantum yield (at t = 0) of energy dissipation
φ_Ro = RE₀/ABS = φ_Po. ψ_Eo. δ_Ro = φ_Po. (1–V_I)	quantum yield for reduction of the end electron acceptors at the PSI acceptor side (RE)
δ_Ro = RE₀/ET₀ = (1 – V_I)/(1 – V_J)	probability that an electron is transported from the reduced intersystem electron acceptors to the final electron acceptors of PSI
γ_RC = Chl_RC/Chl_total = RC/(ABS+RC)	probability that a PSII Chl molecule functions as RC
Phenomenological energy fluxes (per excited leaf cross-section-CS)
ABS/CS = Chl/CS	absorption flux per CS
TR₀/CS = φ_Po. (ABS/CS)	trapped energy flux per CS
ET₀/CS = φ_Po. ψ_Eo. (ABS/CS)	electron transport flux per CS
Density of RCs
RC/CS = φ_Po. (V_J/M₀). (ABS/CS)	Q_A-reducing RCs per CS
Q_A-reducing centers = (RC/RC_reference).(ABS/ABS_reference) = [(RC/CS)_treatment/(RC/CS)_control]. [(ABS/CS)_treatment/(ABS/CS)_control]	The fraction of Q_A-reducing reaction centers
Non-Q_A-reducing centers = 1- Q_A-reducing centers	The fraction of non-Q_A-reducing reaction centers, also so-called heat sink centers or silent centers
S_m/t_FM = [RC_open/(RC_close + RC_open)]av = [Q_A/Q_A(total)]av	average fraction of open RCs of PSII in the time span between 0 to t _{F_M}
R_J = [ψ_{Eo (control)} − ψ_{Eo (treatment)}]/ψ_{Eo (control)} = [V_{J (treatment)} – V_{J (control)}]/[1 − V_{J (control)}]	number of PSII RCs with Q_B-site filled by PSII inhibitor
Performance indexes
$P I_{A B S} \equiv \frac{γ_{R C}}{1 - γ_{R C}} \cdot \frac{φ_{P o}}{1 - φ_{P o}} \cdot \frac{ψ_{E o}}{1 - ψ_{E o}}$	performance index (potential) for energy conservation from photons absorbed by PSII to the reduction of intersystem electron acceptors
$P I_{t o t a l} \equiv P I_{A B S} \cdot \frac{δ_{R o}}{1 - δ_{R o}}$	performance index (potential) for energy conservation from photons absorbed by PSII to the reduction of PSI end acceptors

Subscript “0” (or “o” when written after another subscript) indicates that the parameter refers to the onset of illumination, when all RCs are assumed to be open.