Photon Systems Instruments AquaPen-C AP 110-C, Instruction Manual

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5.1.5 L
IGHT CURVE
(LC)
PROTOCOLS
The protocols called Light Curve (LC) were 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).
Three predefined LC protocols are available. These differ in number and duration of individual light phases and light intensities as shown
in Table 2 below. The visual representation of the LC1 and LC2 protocols is shown in Fig. 9 and belowFig. 10.
# of phases Phase duration Light intensities [µmol.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
Table 2 LC protocols.
The LC protocols include the following measured and calculated parameters:
Abbreviation Explanation
F
0
minimum fluorescence in dark-adapted state
F
m
maximum fluorescence in dark-adapted state
F
m
_Ln
‡
maximum fluorescence in light adaptation state
F
t
_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 phases
*Calculated as (F
m
– F
0
) / F
m
** Calculated as (F
m
_Lx – F
t
_Lx) / F
m
_Lx