Influence of certain environmental factors on photosynthesis and photorespiration in Simmondsia chinensis |
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Authors: | G J Collatz |
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Institution: | (1) Department of Environmental Biology, Research School of Biological Sciences, Australian National University, 5601 Canberra City, A.C.T., Australia;(2) Department of Biological Sciences, Stanford University, 94305 Stanford, CA, USA;(3) Present address: Department of Plant Biology, Carnegie Institution of Washington, 94305 Stanford, CA, USA |
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Abstract: | The response of net photosynthesis and apparent light respiration to changes in O2], light intensity, and drought stress was determined by analysis of net photosynthetic CO2 response curves. Low O2] treatment resulted in a large reduction in the rate of photorespiratory CO2 evolution. Lightintensity levels influenced the maximum net photosynthetic rate at saturating CO2]. These results indicate that CO2], O2] and light intensity affect the levels of substrates involved in the enzymatic reactions of photosynthesis and photorespiration. Intracellular resistance to CO2 uptake decreased in low O2] and increased at low leaf water potentials. This response reflects changes in the efficiency with which photosynthetic and photorespiratory substrates are formed and utilized. Water stress had no effect on the CO2 compensation point or the CO2] at which net photosynthesis began to saturate at high light intensity. The relationship between these data and recently published in-vitro kinetic measurements with ribulose-diphosphate carboxylase is discussed.Abbreviations
C
w
intracellular CO2 concentration
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F
gross
gross photosynthesis
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F
net
net photosynthesis
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I
light intensity
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R
L
light respiration rate
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r
c
carboxylation resistance
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r
8
leaf gas-phase resistance
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r
i
intracellular resistance; to CO2 uptake
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r
t
resistance to CO2 flux between the intercellular spaces and the carboxylation sites
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T
L
leaf temperature
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t
leaf water potential
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CO2 compensation point |
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Keywords: | Gas exchange Oxygen inhibition Photorespiration Photosynthesis Simmondsia Water stress |
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