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Table 1 Commonly used abbreviations and equations employed when measuring chlorophyll fluorescence

From: High throughput procedure utilising chlorophyll fluorescence imaging to phenotype dynamic photosynthesis and photoprotection in leaves under controlled gaseous conditions

Parameter

Formula

Definition

F, F′, Fs′

n/a

Steady state fluorescence emission from dark- or light-adapted (‘) leaf, respectively. F′ is sometimes referred to as Fs′ when at steady state.

Fm, Fm′

n/a

Maximal chlorophyll fluorescence measured in a dark- or light-adapted state respectively

F o , F o ′

n/a

Minimal chlorophyll fluorescence measured in a dark- or light-adapted state respectively

F v , F v ′

n/a

Variable chlorophyll fluorescence measured as the difference between dark- or light-adapted Fm/Fm′ and Fo/Fo′.

Fv/Fm

(Fm–Fo)/Fm

Maximum quantum efficiency of PSII.

Fv′/Fm′

(Fm′–Fo′)/Fm′

Maximum efficiency of PSII in the light.

Fq′/Fm′

(Fm′–F′)/Fm′

PSII operating efficiency: the quantum efficiency of PSII electron transport in the light. AKA ΦPSII, quantum yield or ΔF/Fm′

ETR or J

ΦPSII (AKA Fq′/Fm′) × PPFDa × (0.5)

Linear electron transport rate; where PPFDa is absorbed light (μmol m−2 s−1) and 0.5 is a factor that accounts for the partitioning of energy between PSII and PSI.

NPQ

(Fm–Fm′)/Fm′

Non-photochemical quenching: estimates the rate constant for heat loss from PSII.

qL

(Fq′/Fv′)/(Fo′/F′)

Estimates the fraction of open PSII centers (QA oxidized); considered a more accurate indicator of the PSII redox state than qP

qP

(Fm′–F′)/(Fm′–Fo′) AKA Fq′/Fv′

Photochemical quenching: relates PSII maximum efficiency to operating efficiency. Non-linearly related to proportion of PSII centers that are open. 1–qP has also been used to denote proportion of closed centers

  1. A summary table of the commonly used chlorophyll fluorescence parameters and corresponding equations. For a more comprehensive review please refer to Murchie and Lawson [21], Baker [20] and Maxwell and Johnson [22]