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Measurement of phytoplankton photosynthesis rate using a pump-and-probe fluorometer

100%
Antal T. K., Venediktov P. S., Matorin D. N., Ostrowska M., Wozniak B., Rubin A. B.
Oceanologia
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2001
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tom 43
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nr 3
291-313
In this work we have studied the possibility of determining the rate of phytoplankton photosynthesis in situ using a submersible pump-and-probe fluorometer in water areas differing in their trophic level, as well as in climatic and hydrophysical characteristics. A biophysical model was used to describe the relationship between photosynthesis, underwater irradiance, and the intensity of phytoplankton fluorescence excited by an artificial light source. Fluorescence intensity was used as a measure of light absorption by phytoplankton and for assessing the efficiency of photochemical energy conversion at photosynthetic reaction centers. Parameters of the model that could not be measured experimentally were determined by calibrating fluorescence and irradiance data against the primary production measured in the Baltic Sea with the radioactive carbon method. It was shown that the standard deviation of these parameters in situ did not exceed 20%, and the use of their mean values to estimate the phytoplankton photosynthetic rate showed a good correlation between the calculated and measured data on primary production in the Baltic (r = 0.89), Norwegian (r = 0.77) and South China (r = 0.76) Seas.
2
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Influence of cadmium dose and form on the yield of oat (Avena sativa L.) and the metal distribution in the plant

84%
Tuma J., Skalicky M., Tumova L., Flidr J.
Journal of Elementology
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2014
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tom 19
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nr 3
The influence of two levels of artificial Cd soil contamination (2 and 20 mg Cd kg-1 of soil) on the weight of oat plants, chlorophyll content in leaves, rate of photosynthesis, stomatal conductivity and transpiration rate was researched in a pot experiments with Avena sativa L. Another objective was to detect the effect of cadmium contamination of soil on the content of cadmium in the dry mass of oat panicles, stems, upper green and bottom yellow leaves and roots. The soil contamination was applied in the forms of nitrate Cd(NO3)2, chloride CdCl2 and sulphate CdSO4 2-. High correlation was found between the measured levels of photosynthesis rate, stomatal conductivity and transpiration rates, but no correlation occurred between these levels and the cadmium content in leaves. In the variants with Cd contamination, insignificantly higher levels of photosynthesis rates were observed in the measurements than in the zero variant. A 10-fold higher Cd application dose significantly manifested itself by a higher content of Cd in all the analyzed parts of plants, including generative organs. A several-fold higher Cd level was found in the roots than in other parts of the plant, whereas the lowest Cd content was observed in panicles. However, the results obtained by measuring the cadmium content in stems and green leaves were not significant. In most treatments, a notably higher Cd content was determined in bottom yellow leaves than in upper green leaves. This indicates Cd accumulation in senescent tissues and its difficult reutilization. The highest variance was discovered in treatments with the accompanying SO4 2- anion. While estimating the effect of accompanying anions on the Cd content, significant differences were observed only under the higher level of Cd contamination. The increase in the Cd content in bottom yellow leaves after CdSO4 application was significant when compared with the treatment in which Cd(NO3)2 was applied and insignificant versus the variant with CdCl2. On the other hand, a higher and more significant content of Cd in phtosynthetically active green leaves was measured in the treatment with CdCl2 than with Cd(NO3)2.
3

Chlorophyll fluorescence as a tool in selection of maize lines for hybrids with a high CO2 assimilation under chilling conditions

84%
Koscielniak J., Janowiak F., Kurczych Z.
Polish Journal of Natural Sciences. Supplement
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2003
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tom 01
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