PP Systems CIRAS-2 - Page 125

Brief Introduction to Chlorophyll Fluorescence
CIRAS-2 Operator's Manual Version 2.04
- 123 -
OJIP Fluorescence Induction Curve
Without adequate time-resolution the “J”-peak is often mistaken as the fluorescence
origin (Fo) leading to inaccurate calculation of derived parameters such as Fv and
Fv/Fm (see parameters glossary).
Changes in the magnitude of the “J”-peak following multiple pulse tests are currently
thought to provide a particularly sensitive indicator of photosynthetic stress.
Determination of key fluorescence parameters requires an instrument with:
Fast enough time resolution (10 µs)
To capture the rapid phases at the start
of the Kautsky Curve.
Powerful light source
A light source providing a minimum of
2,500 µmol m
-2
s
-1
to fully reduce all of the
PSII electron acceptors molecules.