Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10939242 | Flora - Morphology, Distribution, Functional Ecology of Plants | 2011 | 6 Pages |
Abstract
An optode device for net-photosynthesis measurements, based on oxygen-depending quenching of fluorescence from O2-specific sensors, and PAM fluorometry have been used to study diurnal courses of net-photosynthesis and the Fv/Fm ratio of the submerged plant Lagarosiphon major. Plants were pre-cultivated and studied in large mesocosm flow-through outdoor tanks under 50% and 80% shade cloth, respectively. Growth under the different shade cloths resulted in similar light compensation points (â¼20 μmol photons mâ2 sâ1), but strongly different light saturation levels, with about 150 μmol mâ2 sâ1 for plants grown under 80% shade cloth and about 350 μmol mâ2 sâ1 for plants grown under 50% shade cloth. Plants under both growth conditions showed a transient reduction of the maximum Fv/Fm value in the afternoon (down to 70% of the morning control values under 80% shade cloth and down to 85% under 50% shade cloth), which was not accompanied by a reduction of the net photosynthetic rate. This indicated that the fluorescence parameter Fv/Fm must not be a reliable indicator of the rate of photosynthesis under all conditions. The new photo-optical device became evidenced as a valuable tool not only for laboratory experiments, but also for field studies of gas exchange of submerged plants.
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Authors
Andreas Hussner, Deborah Hofstra, Peter Jahns,