Observing and Recording Leaf Gas Exchange
CIRAS-2 Operator's Manual Version 2.04
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Enable Recording Blocks
Also available in the Settings Editor (Recording Options button), and is shown when Recording is selected
from the Main Menu.
Recording Blocks of Data at Pre-set Intervals
In this mode, a block of data will be taken after the elapse of the Interval (and optionally after Steady Pn
has been reached). The block of data consists of a number of records to be taken at a specified
frequency. The software will continue recording until stopped. The „Enable Recording Blocks‟ option must
be Selected, and the Record Interval and Frequency entered in seconds. Enter the number of records to
take.
For example:
Interval between blocks = 30 seconds.
Number of Records in a block = 10.
Frequency these records are taken = 5 seconds.
The total time for a block of take to be taken is therefore 80 seconds (30 + (10 * 5)), with records being
taken over a 50 second period.
In the Recording window you will be prompted to ‟Press “Start” when steady‟. Press the Start button
when the Data Display and Control values appear stable. Plots are marked by an „x‟ at each timed
recording event.
Suspending and Resuming Recording
It is possible to suspend recording to allow you to change Control Setpoints while in Timed Recording.
Click the Pause button to suspend recording - make your new Setpoint selection(s), allow the leaf to
reach a stable condition, then click the Cont. (Continue) button to resume recording. To terminate Timed
Recording, click the Stop button.
Response Curve
This option allows you to design highly individualized leaf chamber conditions for experiments in which
CO
2
, H
2
O, temperature and light are automatically controlled and leaf responses recorded. A response
curve consists of as many as 30 predefined levels, each level containing control values determined by
you. Records are taken once the values have been set and a defined (or user initiated) interval has
elapsed. Level-to-level changes can be made uniformly over a concentration range or they may be
specifically defined by the user. Automated A/Ci, A/I and temperature response experiments are typical
applications that utilize a response curve. It is also possible to modify several control values to generate,
for example, Temperature and Light Responses.
When generating Response Curves, it is important to bear in mind the that large changes in a level may
cause CIRAS-2 to Zero or Diff Bal during recording, effectively interrupting the measurement. In some
cases, a Manual Response may be more suitable than an Automatic Response, as the user initiates
recording in a Manual Response where leaf stability may be monitored.
To facilitate transitions between large CO
2
and H
2
O level changes (changes that prompt CIRAS-2 to
automatically perform a Diff Bal) you can predefine the absolute CO
2
and H
2
O ranges of any experiment
by running a Stored Diff Bal prior to any Response Curve. Refer to Stored Diff Bal on page 78. Please
note: In the Settings dialog you must also change the Zero/Diff Bal Mode setting to „Auto Zero with
Stored Diff Bal‟.
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