Chlorophyll Fluorescence

What it does

A calculator that takes raw fluorescence values measured with a PAM fluorometer and derives Fv/Fm, ΦPSII, NPQ, qP, qL, qN and ETR, with a healthy/stress interpretation. It also has a measurement log that saves readings to your facility.

When to use it

Use it after taking dark-adapted, light-adapted or rapid light curve readings to turn raw F₀, Fm, Fs and Fm′ values into standard parameters. The interpretation is advisory, not a species-calibrated threshold.

How it calculates

• Fv/Fm = (Fm − F₀) / Fm; ΦPSII = (Fm′ − Fs) / Fm′
• ETR = ΦPSII × PAR × leaf absorptance × fraction to PSII. With the defaults (0.84 and 0.5) it is reported as relative ETR (rETR)
• NPQ = (Fm − Fm′) / Fm′; qP = (Fm′ − Fs) / (Fm′ − F₀′); qL = qP × F₀′ / Fs; qN = (Fm − Fm′) / (Fm − F₀′). If F₀′ is blank, it is estimated with Oxborough-Baker
• Rapid light curve: Jassby-Platt fit rETR = rETRmax · tanh(α · PAR / rETRmax), drawn only across the measured PAR range

What you enter

F₀ — minimal fluorescence(dark-adapted)

Fm — maximal fluorescence(dark-adapted)

Fs — steady-state fluorescence(light-adapted)

Fm′ — maximal fluorescence(light-adapted)

PAR at the leaf(µmol m⁻² s⁻¹, optional)

F₀′ — light-adapted minimal fluorescence(optional)

Rapid light curve steps: PAR and ΦPSII(at least 3)

Leaf absorptance

Fraction to PSII

Instrument CSV import(MultispeQ, LI-600, Walz PAM)

What you get

Fv = Fm − F₀

Fv/Fm

ΦPSII(operating yield)

ETR(µmol e⁻ m⁻² s⁻¹, relative or absolute)

Fv′/Fm′

NPQ, qP, qL, qN

rETRmax, α (initial slope), Ek and r²

Healthy/stress interpretation(advisory)

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