|
Fv
|
Fm – Fo
|
Variable fluorescence, the ability of PSII to perform photochemistry |
|
Fv′ |
Fm′ – Fo′ |
|
Fq′ |
Fm′ – Ft′ |
Photochemical quenching of fluorescence by open PSII centers |
|
Fv/Fm
|
(Fm – Fo)/Fm
|
Maximum quantum efficiency of PSII |
|
Fv′/Fm′ |
(Fm′ – Fo′)/Fm′ |
Estimate of the maximum quantum efficiency of PSII under actinic light |
| ΦPSII
|
Fq′/Fm′ |
PSII quantum efficiency: the proportion of light absorbed by chlorophyll used for PSII photochemistry |
| qP |
Fq′/Fv′ |
Coefficient of photochemical quenching: relates PSII maximum efficiency to PSII operating efficiency |
| qL |
(Fq′/Fv′)/(Fo′/Ft′) |
Estimates the fraction of open PSII centers |
| NPQ |
(Fm/Fm′) – 1 |
Nonphotochemical quenching constant: estimates the rate constant for heat loss from PSII |
| Rfd
|
(Fp/Ft′) – 1 |
Fluorescence decline ratio calculated using steady-state fluorescence: correlates with CO2 fixation rate, with Rfd > 3 indicative of highly efficient PSII and Rfd < 1 reflecting negligible net CO2 gain; this correlation allows this to be used as a vitality index; here, Fp is taken during the initial phase of the Kautsky effect, where the peak fluorescence is induced by actinic light |
