Observing and Recording Leaf Gas Exchange
CIRAS-2 Operator's Manual Version 2.04
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„Settle‟ refers to the time needed for the leaf to reach a stable (physiological) condition from which reliable
measurements can be recorded, and defines the wait before recording at the next level begins. Level
Settle time is best determined prior to beginning Response Curve recording by pilot testing the
plant/species of interest, using the expected range of CO
2
concentration, light intensity, etc. Large interval
changes and delayed or lagging leaf physiological responses must have correspondingly longer „Settle‟
times associated with them. If it is known that a plant responds quickly to changes in light intensity, for
example, the Level Settle time can be decreased. Also, if a change in CO
2
concentration is small, then a
shorter level settle time can be set.
It is important to bear in mind that changing CO
2
concentrations, etc. may result in time delays of variable
length in order
to „propagate‟ through the system. Therefore, it is advisable to test the Response Curve
prior to running an experiment to ensure that adequate Level Settle times are set. The al
lowable „Settle‟
time range is from 10 to 3600 seconds.
Note that there are 3 buttons in the lower left hand corner of the Response Editor Window:
+
Same as
Increment
=
Same as
Set Equal
-
Same as
Decrement
On/Off
Same as
Toggle Enable
Editing Groups of values
If several adjacent values from the same row are selected, the
Enter _ Value
dialog box will appear.
Editing Individual values
To introduce non-incremental values into Response Levels click inside any individual CO
2
, H
2
O, Temp.,
PAR or Settle cell. The current parameter, its value and Response Level are displayed in the upper left
field (see below). Enter the new value in the field and click on the cell again to register the value in the cell
for that specific Response Level. Customize additional Response Levels as desired.
