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Title
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The effect of long-term exposure of **Lolium perenne** L. plants to elevated and/or elevated air temperature on quantum yield of photosystem 2 and net photosynthesis
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Author
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Abstract
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| The effects of long-term exposure of Lolium perenne L. plants to CO2 concentration elevated to 700 mu mol (CO2) mol(-1) (EC) and air temperature elevated by 4 degrees C (ET) on the quantum yield of electron transport of photosystem 2, PS2 (phi(2)) and on the potential yield of photochemical reactions of PS2 (F-v/F-m) measured by the chlorophyll (Chl) fluorescence method, were studied. The plants were exposed for 6 months in opened field greenhouses to four treatments simulating global atmospheric changes: (1) ambient CO2 (AC) and ambient air temperature, AT (ACAT - control), (2) EC and AT (ECAT), (3) AC and ET (ACET), and (4) EC and ET (ECET). When the plants were exposed to stepwise increased irradiance, a decrease in phi(2) was found under both AC and EC measuring concentrations. At high irradiances a significantly higher yield of PS2 was detected when measured under EC compared to AC regardless of long-term CO2 and temperature treatment (i.e., positive short-term. effect of EC). The short-term effect of EC on phi(2) as related to net photosynthetic rate (P-N) Shift was detected from irradiance response curves. At high irradiances and AC, phi(2) was reduced in comparison to control for the plants of EC and ET treatments (i.e., negative long-term effect of treatment). The long-term effect of both EC and ET on the yield of PS2 was attributed to a down-regulation of P-N caused by the treatment. The phi(2) was related to the actual rate of photosynthesis and the relationship between phi(2) and phi(CO2) was linear over a wide range of irradiances. No effect of long-term treatments on the dark-adapted F-v/F-m ratio was found in plants cultivated under natural greenhouse irradiance. |
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Language
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English
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Source (journal)
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Photosynthetica. - Praha
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Publication
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Praha
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1996
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ISSN
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0300-3604
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Volume/pages
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32
:4
(1996)
, p. 549-562
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ISI
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A1996VM34000008
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