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New -automated modulation light set up
Auto Gain – On the set up screen. This option automatically adjusts the modulated light
setting to a detection range that will work for the sample. Press “Auto Gain” and the
instrument automatically goes through a routine that sets the modulation intensity
correctly. A leaf must be in the PAR Clip or open body clip when this routine is running.
Yield Test Setup Screen
Setting the saturation pulse intensity - Values can be set from 5% to 100% in
5% increments. At 100%, the intensity of the saturation pulse is approximately 11,000
umols when used with a dark clip. Saturation intensity is approximately 6,200 umols
when used with a PAR Clip.
Setting saturation pulse duration
Press the graphic screen display of the measuring trace. Duration is the time that the
saturation flash is turned on. For higher plants, times of 0.5 to 1.5 seconds have been
used. The optimal saturation duration for algae and cyanobacteria is between 25 and 50
msec. (Schreiber 1995). If the duration is not long enough, then PSII is not fully
saturated, even at the highest intensity, and Fm values are reduced. If the Duration is too
long, on most chlorophyll fluorometers, the saturation pulse peak becomes subject to a
type of NPQ that rounds the tailing edge of the saturation peak and also reduces the
average Fm value. The Ideal saturation pulse peak is flat on the top with the trailing edge
rounding minimized (Roseqvist and van Kooten 2006).The OS1p provides an automation
feature that uses a rolling continuous eight point average to find the highest average value
on the top of the saturation pulse. These eight points represent a time of 25 msec. As a
result, the optimal saturation duration is automatically provided for higher plants, algae
and cyanobacteria if the duration is long enough. 0.8 seconds is adequate for most plants.
The saturation pulse duration is adjustable between 0.1 and 2.0 seconds.
To adjust the duration, touch the upper right graphic display window of the Y(II)
measuring window.
To adjust the duration, touch the upper right graphic display window of the Yield
protocol measuring window.
To use the automated modulation light setup mode, press
“Auto Gain”. The system then adjusts the modulation light
source into an acceptable minimum reading range for the
PIN diode detector.
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