(ABSTRACT1)

PHOTOSYNTHETIC CHARACTERISTICS OF THE AQUATIC CARNIVOROUS PLANT ALDROVANDA VESICULOSA

Carnivorous Plant Newsletter 26: 104-105 (1997)

 

LUBOM═R ADAMEC

 

Academy of Sciences of the Czech Republic, Institute of Botany, Dukelskß 135, CZ-379 82 T°ebo˛, Czech Republic

 

Keywords: chemistry: habitat - field studies: Aldrovanda vesiculosa - field studies: photosynthesis.

 


Aldrovanda vesiculosa L. is a critically endangered aquatic carnivorous plant. It is considered to be strictly stenotopic. Chemical and physical factors were measured in situ in Aldrovanda stands at eight Polish sites. There, the oxygen concentration usually ranged between 0.25-0.28 mM. There was a very wide range of pH of 5.04-7.60. but with a median of 7.17. The total alkalinity ranged between 0.16-4.2 meq 1-1 but was mostly within 1.0-2.7 meq 1-1. A high CO2 concentration was typical in all stands; it ranged between 0.14-3.5 mM and was usually within 0.2-0.5 mM. Aldrovanda grew in unshaded stands and in areas shaded by emergent vegetation, where only about 18-24 % of incident irradiance penetrated to the water surface. Aldrovanda can therefore tolerate various levels of oxygen, pH, total alkalinity, and shading but requires a high CO2 concentration (i.e. above about 0.14 mM). This is the most important condition for its very fast apical growth. Laboratory photosynthetic study revealed that Aldrovanda was a strict CO2 user; its CO2 compensation point of photosynthesis was 5.9-8.2 microM. Its net photosynthesis depended on CO2 according to the Michaelis-Menten kinetics. The Km was 165▒77 microM CO2 and the maximum photosynthesis 99▒10 mmol kg-1 (FW) h-1. Thus, it is a CO2 user and high CO2 concentration in the environment can ensure rapid growth. It was found to be markedly photophilous: its light compensation point was 6.0 W m-2 of PAR. Photosynthetic rates rose from 15 to 34░C. The highest photosynthetic rate was found in young apical shoot segments and it declined toward the bases.

 

Lake

n

[O2]

pH

TA

[CO2]

PAR

 

 

(mM)

 

(meq 1-1)

(mM)

(%)

Miklaszˇwek

8

0.30

7.33

4.23

0.44

24(3)

 

 

0.24-0.34

7.19-7.60

 

0.24-0.62

 

Kruglak

4

0.28

7.25

2.67

0.35

36(3)

 

 

0.18-0.39

7.14-7.46

 

0.22-0.48

 

Orle

1

0.27

7.30

2.42

0.27

n.d.

Krzywe

1

0.26

7.59

2.50

0.14

n.d.

Ostrowo

5

0.29

7.10

1.60

0.28

33(1)

 

 

0.26-0.34

7.00-7.28

 

0.18-0.36

 

Dlugie

3

0.26

5.93

1.01

2.55

n.d.

 

 

0.23-0.30

5.80-6.40

 

1.09-3.35

 

Moszne

2

0.09

5.69

0.57

2.80

n.d.

 

 

0.022-0.15

5.68-5.70

 

2.44-3.16

 

Brzeziczno

1

0.08

5.04

0.16

3.50

n.d.

Mean

0.26

6.15

1.75(12)

0.94

31(7)

Median

0.27

7.17

1.60

0.39

28

Total Range

0.022-0.39

5.04-7.60

0.2-4.2

0.1-3.5

18-49

 

Mean values and ranges of values are shown and the number of measurements are shown in brackets. Total mean and range of values are also shown.

n, number of investigated stands.

TA, total alkalinity.

PAR, % of incident light penetrating to the water surface.

[CO2], CO2 concentration calculated from pH and total alkalinity.

n.d., not determined.

 

lFrom Aquatic Botany, 59: 297-306 (1997), with kind permission from Elsevier Science NL, Amsterdam, The Netherlands. 


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