ul 2004
nificant.
ove the
yunt.
nmental
ion and
1d work
aken. In
ne fiber
he first
CES
ırable
onths
yrevious
aks of
s in the
sensor.
peatedly
F4)
987
928
942
977
934
F4)
,023
‚029
‚016
‚017
,019
phyll in
nfluence
, on the
s. Thus,
'ence of
lation of
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
quantities of such material that has been extracted from soil by
plants.
Chlorophyll is a colorant which is produced by plants for the
use of light energy. It consists of two parts: an non-polar part
with which chlorophyll is fixed to the membrane of chloroplasts
and a complex polar part from which the color results,
(http://www.net-lexikon.de/Chlorophyll.html).
There are different types of chlorophyll with different
absorption spectra and occurrence:
e Chl a: blue-green, chlorophyta (green alga, land plants)
e Chl b: green, chlorophyta (green alga, land plants)
e Chl c: yellow-green, phaenophyta (brown alga)
e Bacteriochlorophyll b: cyano bacteria
In photosynthesis the energy of light is transferred to an
electron in the active center between two coupled chlorophyll a-
molecules, while chlorophyll b is mainly responsible for
collecting and transferring light to the active center.
In land plants only chlorophyll a and b is produced. So suitable
techniques have to be applied for the extraction of the
molecules out of the leaves. Firstly, the leafs are cut up small
and under addition of calcium carbonate (CaCO;) and acetone
triturated in a cooled morter. After the first destruction of the
leaf structure the breakup is continued by adding further
acetone. The material is finally centrifuged for ten minutes. The
clear, deep-green supernatant which contains all pigments is
decanted to a cuvette for the transmission measurement.
The chlorophyll concentration in mg:ml' results from the
measured transmission of the probe at specific wavelengths
from (Arnon 1949 and Porra 2002):
CHLG) «(0175 * E o) ~ (2.35 EL) (3)
CHL(b) » (18,61* E,,,) — (3.96 * E¢,)
For control purposes the probes have been measured by the
TriOS sensor and a calibrated laboratory photometer (Perkin
Elmer UV/Vis Spectrometer Lambda 20 with Software
UVWinlab). With the sensor system and the formulae described
above the results shown in Appendix C have been achieved.
The results comply with the expected accuracy of less than 10
% of the chlorophyll concentration. This proves that the sensor
system and the measurement setup used is suitable for this task.
Furthermore, it can be observed that considering the offset of -
0,014 in the transmission values does not improve the results
significantly.
3. CONCLUSIONS
When acquiring spectral information from plants the relevant
parameter is the ratio of incident and reflected or transmitted
illumination. For field work the problem of simultaneous
measurement of both intensities has to be solved or a closed
sensor system has to be used.
By using calibrated cuvettes and fiber optic cables spectral
resolution and intensity accuracy of a sensor system can be
easily verified in the visible range by a laboratory test. Fiber
optic cables must be used in a constant order and direction to
avoid any effects or irregularities in the optical pathway.
91
The use of low-cost spectrometers normally accomplishes the
required accuracy and reliability for applications with plants
like precision agriculture or phyto-remediation. The quality of
the instrumentation allows for a long term use in filed-work.
There, a rapid test with defined material with a known spectral
behavior (spectral standard) can be carried through.
Further research work has to be done to analyze some effects
concerning the spectral behavior of the light source. Within the
limits of accuracy of a highly precise laboratory photometer the
light source remained constant for a longer observation epoch.
Nevertheless, differences in the intensities were noticeable
between different epochs.
4. LITERATURE
Arnon, D. I. 1949. “Copper enzymes in isolated chloroplasts”,
Plant Physiol. 24, ] -15.
DIN 5036 Teil 1, 1978. “Strahlungsphysikalische und
lichttechnische Eigenschaften von Materialien", Beuth Verlag
GmbH Berlin Kóln.
Fiedler, HJ. 2001. *Bóden und Bodenfunktionen: in
Ókosystemen und Ballungsráumen*, Expert Verlag, ISBN: 3-
8169-1875-1.
Porra R. J., 2002. “The chequered history of the development
and use of simultaneous equations for the accurate
determination of chlorophylls a and b”, Photosynthesis
Research 73.
Scheffer, F. 2002. “Lehrbuch der Bodenkunde®, Spektrum
Akademischer Verlag Heidelberg, ISBN: 3-8274-1324-9.
Weisensee, M. 1992. "Modelle und Algorithmen für das
Facetten-Stereosehen", DGK, C, 374.
http://www.net-lexikon.de/Chlorophyll.html,
(accessed: 28.04.2004).
