Making Measurements
Some Simple Experiments
4-12
Using the LI-6400
4
8
Change the temperature control to a 5¡C
Before you do, test your understanding with this question:
Question #8:
How will flow rate respond as the temperature increases, since
weÕre holding a constant vapor pressure deficit? (Answer on page 4-53.)
Now try it, and see who is correct. Wait 2 or 3 minutes for things to stabilize.
9
Watch it warm
You might notice that warming is more efficient than cooling. You may also
notice that the VPD gets away from the target a little bit as the temperature
changes.
When the block temperature achieves its target, see that the VPD settles back
to itÕs target. Then set the target temperature to ambient, and bring the cham-
ber back to normal.
You can turn the temperature control off if you like.
Controlling CO
2
The next two experiments are best done with a 6400-01 CO2 mixer. If you
donÕt have one installed, you can still do approximate CO
2
control between
ambient and zero by adjusting the soda lime tube flow adjust knob.
Experiment #3
CO
2
and Humidity Control Interactions
Start with the conditions described by
the desiccant knob is mid-range.
1
Set flow control for constant water mole fraction
Target the current value of
H2OS_mml
Points to Remember
¥ Constant humidity mode will compensate for changes in incoming air
stream, or leaf transpiration changes.
¥ Controlling to a constant mole fraction is the tighter control, while con-
trolling to a constant RH or VPD can have small lags in the face of rapidly
changing temperature (see the discussion about the various humidity con-
trol options on page 7-10 for more details).
Summary of Contents for LI-6400
Page 1: ...Using the LI 6400 Portable Photosynthesis System ...
Page 15: ...Part I The Basics ...
Page 16: ......
Page 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Page 175: ...Part II Useful Details ...
Page 176: ......
Page 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Page 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Page 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Page 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Page 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Page 289: ...Part III Working With Files ...
Page 290: ......
Page 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Page 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Page 375: ...Part IV Configuration Issues ...
Page 376: ......
Page 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Page 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Page 455: ...Part V Maintenance Troubleshooting ...
Page 456: ......
Page 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Page 593: ...Part VI Programming ...
Page 594: ......
Page 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Page 846: ...Index I 16 Using the LI 6400 ...