Observing and Recording Leaf Gas Exchange 
 
CIRAS-2 Operator's Manual Version 2.04 
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more of the calculated physiological variables.  In the sample screen (above) the currently active plot is Cd 
(black)  with  the  Y-axis  scale  set  to  +5  to  -50,  to  capture  both  respiration  (positive  differentials)  and 
photosynthesis (negative differentials). 
 
To include additional information about your experiment or treatment click the   T   button and enter the 
information by selecting a particular “Treatment” associated with the measurement. 
 
 
 
 
 
To end measurements, press the Stop button.  The following will be displayed: 
 
 
 
 
 
Click Yes to terminate measurements. 
 
Keypress Recording 
For many leaf gas exchange measurements, such as those made in the field and under dynamic light 
conditions, this method of recording is most practical. Using this method you can record measurements in 
rapid  succession  with  either  the  thumb  record  switch on  the  cuvette handle  or  by clicking  the  Single 
button in the CIRAS-2 Recording Mode screen.  To begin manually recording data, click in the circle next 
to „Key Press‟ and then click OK.    
 
In Keypress Recording mode the appearance of data markers in the Time Plot is different depending on 
the source of the record: in the image below the first 3 records (circles with a vertical hash line) on the 
plots, were taken by clicking  Single – the next 3 records (boxes) were taken with the thumb record switch 
on the PLC6(U) cuvette.