Skip to main content
. 2023 Sep 29;11:e16107. doi: 10.7717/peerj.16107

Table 1. Summary of the OJIP-test parameters using data extracted from the fast fluorescence transient.

Fluorescence parameter Calculation
Fo Minimal fluorescence when all photosystem II reaction centers are open (at 50millisecond) –
Fj Fluorescence intensity at the J-step (at 2 millisecond) –
Fi Fluorescence intensity at the I-step (at 30 millisecond) –
Fm (Fp) Maximal fluoresxence intensity when all photosystem II reaction centers are closed –
Vj Relative variable Chl fluorescence (at 2 millisecond) (FJ −Fo)/(FM −Fo)
Vi Relative variable Chl fluorescence (at 30 millisecond) (FI −Fo)/(FM −Fo)
Fv/Fm Maximum quantum yield of PSII photochemistry measured in the dark-adapted state (Fm −F0)/Fm
PIABS Performance index on an absorption basis: the efficiency of energy conservation from absorbed photons to a reduction in intersystem electron carriers (RC/ABS) [(ΦPo/(1 −ΦPo)] [(1 −VJ)/(1 −(1 −VJ))]
Mo Slope at the beginning of the transient FO → FM, maximal fractional rate of photochemistry approximated initial slope (per millisecond) of the fluorescence transient V = f(t). This parameter reflects the rate at which photosystem II reaction centers are closed. It is a net value, because reduced QA can be reoxidized as a result of electron transport outside QA. 4 (F300 −Fo )/(FM −Fo)
Ss Normalized total area above the OJIP curve (reflecting multiple turnover of QA reductions). The Ss minimum appears only when each QA is reduced only once the smallest SM turn-over (single turn-over) Area/(FM −Fo)
Specific fluxes per active PSII reaction center
ABS/RC Average absorbed photon flux per photosystem II reaction center Mo (1/VJ) (1/ ΦPo)
TRo/RC Energy flux trapped by one active photosystem II reaction center Mo (1/VJ)
ETo/RC Rate of electron transport flux from QA to QB per photosystem II reaction center Mo (1/VJ) (1 −VJ)
DIo/RC Energy flux not intercepted by a reaction center ABS/RC −TRo/RC
REo/RC Electron flux leading to a reduction in the PSI end acceptor Mo (1/VJ) (1 −VI)
ΦPo Quantum yield of primary photochemistry; probability that an absorbed photon leads to a reduction in QA (FM −Fo)/FM