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Table 1 Summary of parameters, formulae and their description using data extracted from chlorophyll a fluorescence (OJIP) transient.

From: Salicylic acid alleviates decreases in photosynthesis under heat stress and accelerates recovery in grapevine leaves

Fluorescence parameters Description
F t Fluorescence intensity at time t after onset of actinic illumination
F 50 μs Minimum reliable recorded fluorescence at 50 μs with the PEA fluorimeter
Fk (F300 μs) Fluorescence intensity at 300 μs
F P Maximum recorded (= maximum possible) fluorescence at P-step
Area Total complementary area between fluorescence induction curve and F = Fm
ABS Absorption of energy
TR Trap of energy
CS Excited Cross section
Derived parameters (Selected OJIP parameters)  
FoF50 μs Minimum fluorescence, when all PSII RCs are open
Fm = FP Maximum fluorescence, when all PSII RCs are closed
Vj = (F2 ms -- Fo)/(Fm -- Fo) Relative variable fluorescence at the J-step (2 ms)
Vi = (F30 ms -- Fo)/(Fm -- Fo) Relative variable fluorescence at the I-step (30 ms)
WK= (F300 μs-- Fo/(Fj-- Fo) Represent the damage to oxygen evolving complex OEC
Mo = 4 (F300 μs -- Fo)/(Fm-- Fo) Approximated initial slope of the fluorescence transient
Yields or flux ratios  
ϕPo = TRo/ABS = 1-- (Fo/Fm) = Fv/Fm Maximum quantum yield of primary photochemistry at t = 0
ϕEo = ETo/ABS = (Fv/Fm) × (1 -- Vj) Quantum yield for electron transport at t = 0
ψEo = ETo/TRo = 1 -- Vj Probability (at time 0) that a trapped exciton moves an electron into the electron transport chain beyond QA-
δRo = (1 -- Vi)/(1 -- Vj) Efficiency with which an electron can move from the reduced intersystem, electron acceptors to the PSI end electron acceptors
Density of reaction centers.
RCQA = ϕPo × (ABS/CSm) × (Vj/Mo)
Amount of active PSII RCs (QA-reducing PSII reaction centers) per CS at t = m