PSI FluorPen FP 100, Operation Manual

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9.F. Light Curve (LC) Protocol
The protocol called Light Curve (LC) was designed to acquire parameters for construction of Light
Response Curve relating the rate of photosynthesis to photon flux density. The method is based on
successive measurements of the sample exposed to a stepwise increase of light intensity. The effective
quantum yields of photosynthesis are determined under various light intensities of continuous
illumination. Measurement is based on pulse modulated fluorometry (PAM).
Several LC protocols are predefined in FP. These differ in number and duration of individual light phases
and light intensities.
# of phases Phase duration
Light intensities, [

mol m
-2
s
-1
]
LC1 6 60s 10; 20; 50; 100; 300; 500
LC2 5 30s 100; 200; 300; 500; 1000
LC3 7 60s 10; 20; 50; 100; 300; 500; 1000
The protocol includes following measured and calculated parameters:
Abbreviation Explanation
Fo minimum fluorescence in dark-adapted state
Fm maximum fluorescence in dark-adapted state
Fm_Ln
‡
maximum fluorescence in light adaptation state
Ft_Ln
‡
instantaneous fluorescence during light adaptation
QYmax * maximum quantum yield of PSII in dark-adapted state - Fv/Fm
QY_Ln
‡
** instantaneous PSII quantum yield induced in light
‡
n represents a sequential number of light phase
* Calculated as (Fm – Fo) / Fm
** Calculated as (Fm_Lx – Ft_Lx) / Fm_Lx