Table 1.
List of the OJIP test parameters with explanations and formulae used for calculation according to Kalaji et al. [25,26].
| Parameter | Calculation | Description |
|---|---|---|
| Extracted and technical fluorescence parameters | ||
| Fo | Fluorescence intensity at 50 µs | Fluorescence intensity when all reaction centers (RCs) are open |
| Fj | Fluorescence intensity at 2 ms at J-step | |
| Fk | Fluorescence intensity at 300 µs at K-step | |
| Fm | Maximal fluorescence intensity | Fluorescence intensity when all RCs are closed |
| Vj | Vj = (Fj − Fo)/(Fm − Fo) | Relative variable fluorescence at 2 ms. For unconnected PSII units, this equals the fraction of closed RCs expressed as a proportion of the total number of RCs |
| Vk | Vk = (Fk − Fo)/(Fm − Fo) | Relative variable fluorescence at 300 μs |
| Fv/Fo | (Fm − Fo)/Fo | Proportional to the activity of the water-splitting complex on the donor side of the PSII |
| Fk/Fj | To probe the extent of inactivation of the PSII donor side | |
| Mo | Mo = 4(F300 − Fo)/(Fm − Fo) | Slope of the normalized curve at the origin of the fluorescence rise. Net rate of closed reaction centers accumulation |
| Sm | Sm = Area/(Fm−Fo) | Standardized area above the fluorescence curve between Fo and Fm is proportional to the pool size of the electron acceptors QA on the reducing side of Photosystem II |
| Tfm | Time needed to reach Fm | |
| Efficiencies and quantum yields | ||
| ϕP0 | ϕP0 = 1 − (Fo/Fm) = Fv/Fm | Maximum quantum yield of primary PSII photochemistry. Probability that an absorbed photon will be trapped by the PSII RC with the resulting reduction of QA |
| ϕE0 | ϕE0 = [1 − (Fo/Fm)](1 − Vj) | Quantum yield for electron transport |
| ΨE0 | ΨE0 = 1-Vj | Efficiency of excitation energy to electron transport flux conversion. Probability that an exciton trapped by the PSII RC enters the electron transport chain |
| δR0 | δR0 = (1 − Vi) (1 − Vj) | Efficiency with which an electron from the intersystem electron carriers moves to reduce end electron acceptor side (RE) |
| δD0 | δD0 = 1 − ϕP0 | It expresses the probability that the energy of an adsorbed photon is dissipated as heat |
| ϕR0 | ϕR0 = δR0*ϕP0*ΨE0 | Quantum yield for the reduction of end acceptors of PSI per photon absorbed |