LI-COR LI-6400, Руководство пользователя

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System Description
Equation Summary
Using the LI-6400 1-7
Equation Summary
If you are not interested in the details of the LI-6400Õs gas exchange calcula-
tions, you can safely skip this section.
The equations for net photosynthesis, transpiration, etc. are essentially those
derived by von Caemmerer and Farquhar
1
. Note also that these equations rep-
resent the instrumentÕs defaults, and can be modified or replaced as desired
by the user (Chapter 15).
Transpiration
The mass balance of water vapor in an open system (Figure 1-4) is given by
(1-1)
where s is leaf area (m
-2
), E is transpiration rate (mol m
-2
s
-1
), u
i
and u
o
are
incoming and outgoing flow rates (mol s
-1
) from the chamber, and w
i
and w
o
are incoming and outgoing water mole fractions (mol H
2
O mol air
-1
). Since
(1-2)
we can write
(1-3)
1.
S.von Caemmerer and G.D.Farquhar (1981) Some relationships between the
biochemistry of photosynthesis and the gas exchange of leaves, Planta 153:376-
387
u
i
u
o
E
Figure 1-4. Measuring fluxes in an open system. Transpiration rate E and photo-
synthetic rate a change the water and CO
2
concentrations of air as it passes
through the chamber. Transpiration also causes the exit flow u
o
to be greater than
the incoming flow rate u
i
.
w
i
w
o
a
c
i
c
o
sE u
o
w
o
u
i
w
i
Ð =
u
o
u
i
sE + =
sE u
i
sE +
( )
w
o
u
i
w
i
Ð =