Making Measurements
Some Simple Experiments
4-10
Using the LI-6400
4
serve the new set of values. This
H2OS_mml
value represents your lower hu-
midity limit for this leaf.
How is stomatal conductance (
Cond
) behaving: steady, dropping, or increas-
ing?
Question #3:
We just lowered the humidity in the chamber. If there are water
sorption effects on the chamber walls, will they make stomatal conductance
too high or too low? (Answer on page 4-53.)
Question #4:
How might you differentiate real stomatal changes from water
sorption effects? (Answer on page 4-53.)
6
Return to starting Conditions
Return the flow to 400 µmol s
-1
, and the desiccant to mid-range between
scrub and bypass.
Experiment #2
Maintaining a Constant Humidity
Often it is desired to make measurements or to conduct an experiment at a
consistent chamber humidity. This experiment lets you see the automatic hu-
midity control in action.
1
Pick a humidity target
Start out in fixed flow mode at 400 µmol s
-1
, with the desiccant adjustment
knob midway between scrub and bypass.When
H2OS_mml
is stable, change
to constant humidity control (use the H option: constant H
2
O mole fraction),
and target that current value of
H2OS_mml
. Your flow rate should settle into
the 300 or 400 µmol s
-1
range. (If flow jumps to either extreme, and you start
seeing flashing messages about targets being too dry or too wet, make sure
you selected the H option, and entered a reasonable value in mmol mol
-1
.)
Note the
CO2S_µml
value.
Points to Remember
¥ Changing the flow rate affects both CO
2
and H
2
O concentration in the
chamber.
¥ Chamber humidity control is via flow rate. The highest humidity is
achieved by low flow and bypassing the desiccant. The lowest humidity is
achieved by high flow and full scrub.
Содержание LI-6400
Страница 1: ...Using the LI 6400 Portable Photosynthesis System ...
Страница 15: ...Part I The Basics ...
Страница 16: ......
Страница 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Страница 175: ...Part II Useful Details ...
Страница 176: ......
Страница 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Страница 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Страница 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Страница 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Страница 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Страница 289: ...Part III Working With Files ...
Страница 290: ......
Страница 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Страница 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Страница 375: ...Part IV Configuration Issues ...
Страница 376: ......
Страница 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Страница 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Страница 455: ...Part V Maintenance Troubleshooting ...
Страница 456: ......
Страница 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Страница 587: ...Diagnostics and Utilities Sys Utility Programs Using the LI 6400 21 15 EBVpd t C guess EBSatVap _EBvap_kPa ...
Страница 593: ...Part VI Programming ...
Страница 594: ......
Страница 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Страница 846: ...Index I 16 Using the LI 6400 ...