CIRAS-3 Operation Manual V. 1.09
28
Assuming that you are seeing the same thing then now would be a good time to record a measurement.
Press
Record (F6)
on the CIRAS-3 console or the “
R
” key on the PLC3 to record data and then proceed
to record 5 more measurements on the same leaf. After the 5
th
record press
End Recording F5
. In the
example above there was a reasonable amount CO
2
uptake (CO2d) and small H2Od. If you are testing
on a very healthy, well-watered plant you may see higher differentials for both CO
2
(CO2d) and H
2
O
(H2Od) resulting in higher rates of photosynthesis (A).
How do I know when it is time to record a measurement?
Good question. Generally speaking, the usual rule of thumb is that a healthy leaf reaches equilibrium
when CO
2
differential (CO2d) stabilizes (changing back and forth at same concentration for 5-10
seconds). Normally, this is a good time to record a measurement. The actual equilibration time varies
based on the state of the plant at time of measurement and environmental controls. Having said that,
normal healthy leaves tend to equilibrate and stabilize in approximately 45-60 seconds. In the field and
when working under ambient sunlight conditions it is very important to try and keep the cuvette head in a
steady position throughout the course of measurement to minimize changes in light intensity. Changes in
light intensity will definitely have an impact on photosynthesis. With that being said it is also a good rule
of thumb to maintain the same CO
2
and H
2
O controls and flow rate during each measurement as any
change to environmental conditions and flow rate will have an effect on the plant’s equilibration and
subsequent results.
As mentioned earlier the data was saved to internal memory as an .xml file so that is where we need to
go to retrieve the data. Insert your USB flash drive (supplied by PP Systems) into the USB 2 port as
shown below (actually both USB ports will work just the same).
F1
F3
F2
F4
F6
F5
F7
F8
