116
40
:c
Usnea filipendula;
:E
intact thallus
0
Cl 30
E
N
0
(5 20
E
..=;
II)
·iii
' "
J::
C 10
>.
II)
~
J::
00 0
2
3
4
5
C02 added to the cuvette [%]
B
:;:
:E
0
'"
E
8
(5
E
..=;
II)
·iii
CD
J::
C >.
til
(5
J::
04
3
2
1
0 0
H. Pfanz
Trebouxia usneae;
isolated algae
10
20
30
40
50
60
KHC03 added to the solution [mM]
Fig. 5.4 A,B. Photosynthesis of an intact thallus (A) and of isolated algae Trebouxia
usneae (B) of the lichen Usnea filipendula at various CO2 or KHC03 concentrations in
the medium. Measurements were performed at pH 6.5 in a Clark-type oxygen electrode
either in the gas phase (A) or in solution (B). The algae were freshly isolated from
homogenized material. (After Pfanz and Protte, unpubl.)
to synthetic carbon reduction of a lichen in the presence of an excess of
carbon dioxide. It is seen that, irrespective of whether the CO2 concentration in air was raised over 1.5% (v/v) in the experiment with an intact
Usnea thallus, or the bicarbonate concentration was increased in the incubation medium of freshly isolated Trebouxia algae to values around 5 mM
A
B
25
25r-------------------------~
:;:
Picea: pH 6.0
Picea: pH 8.0
•
:E
20
0
'" E
0'
(5
E
2:
II)
·iii
CD
J::
C ,..
U>
o
~
J::
·5
0-5
-10 0 2 4 6 8 10 12 14 16 18 20
-10 L-__ --'-____ ....L.. ____ .l..-__ ---L ____ ....I
o
20
40
60
80
100
KHC03 added to the solution [mM]
KHC03 added to the solution [mM]
Fig. 5.5 A,B. Photosynthesis of spruce needles at various concentrations of bicarbonate
and two different proton concentrations (pH 8 and 6) of the medium. Measurements were
performed in an oxygen electrode with l-year-old needles of Picea abies that were cut
longitudinally. (After Pfanz and Rumpel, unpubl.)