Table 1.
Summary of parameters, formulae and their description using data extracted from chlorophyll a fluorescence (OJIP) transient.
| Fluorescence parameters | Description |
| Extracted parameters | |
| Ft | Fluorescence intensity at time t after onset of actinic illumination |
| F50 μsor F20 μs | Minimum reliable recorded fluorescence at 50 μs with the PEA- or 20 μs with Handy-PEA-fluorimeter |
| F100 μs and F300 μs | Fluorescence intensity at 100 and 300 μs, respectively |
| FJ and FI | Fluorescence intensity at the J-step (2 ms) and the I-step (30 ms), respectively |
| FP (= Fm) | Maximum recorded (= maximum possible) fluorescence at P-step |
| Area | Total complementary area between fluorescence induction curve and F = Fm |
| Derived parameters | |
| Selected OJIP parameters | |
| Fo ≅ F50 μsor Fo ≅ F20 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) |
| Mo = 4 (F300 μs - Fo)/(Fm - Fo) | Approximated initial slope (in ms-1) of the fluorescence transient V = f(t) |
| VK = (F300 μs - Fo)/(Fm - Fo) | Relative variable fluorescence at 300 μs |
| Sm = ECo/RC = Area/(Fm - Fo) | Normalized total complementary area above the OJIP (reflecting multiple-turnover QA reduction events) or total electron carriers per RC |
| Fraction of OEC = [1 - (VK/VJ)]treated sample/[1 - (VK/VJ)]control | The fraction of oxygen evolving centers (OEC) in comparison with control |
| Yields or flux ratios | |
| φPo = TRo/ABS = 1 - Fo/Fm = Fv/Fm | Maximum quantum yield of primary photochemistry 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- |
| φDo = DIo/ABS = 1 - φPo = Fo/Fm | Quantum yield at t = 0 for energy dissipation |
| δRo = REo/ETo = (1 - VI)/(1 - VJ) | Efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors |
| φRo = REo/ABS = φPo × ψEo × δRo | Quantum yield for the reduction of end acceptors of PSI per photon absorbed |
| Specific fluxes or activities expressed per reaction center (RC) | |
| ABS/RC = Mo × (1/VJ) × (1/φPo) | Absorption flux per RC |
| TRo/RC = Mo/VJ | Trapped energy flux per RC at t = 0 |
| ETo/RC = (Mo/VJ) × ψEo = (Mo/VJ) × (1 - VJ) | Electron transport flux per RC at t = 0 |
| DIo/RC = ABS/RC - TRo/RC | Dissipated energy flux per RC at t = 0 |
| REo/RC = (REo/ETo) × (ETo/RC) | Reduction of end acceptors at PSI electron acceptor side per RC at t = 0 |
| Phenomenological fluxes or activities expressed per excited cross section (CS) | |
| DIo/CSo = ABS/CSo - TRo/CSo | Dissipated energy flux per CS at t = 0 |
| Performance index | |
| PItot,abs = (RC/ABS) × (φPo/(1 - φPo)) × (ψEo/(1 - ψEo)) × (δRo/(1 - δRo)) | Total performance index, measuring the performance up to the PSI end electron acceptors |