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The effects of O 2 on net photosynthesis at low temperature (5°C)
Author(s) -
CORNIC GABRIEL,
LOUASON GENEVIÈVE
Publication year - 1980
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11580938
Subject(s) - photosynthesis , carbon dioxide , chemistry , phytotron , nicotiana tabacum , horticulture , botany , carboxylation , stimulation , oxygen , analytical chemistry (journal) , nuclear chemistry , biology , biochemistry , environmental chemistry , organic chemistry , neuroscience , gene , catalysis
. It has been shown that atmospheric O 2 can either depress or stimulate the rate of apparent photosynthesis of white mustard depending on the environmental conditions: CO 2 concentration, light intensity and temperature. Stimulation by O 2 was observed only under high photon fluence rate and at high CO 2 concentrations. The critical CO 2 concentration below which O 2 was inhibiting and above which it was stimulating was dependent on the temperature of the assay: for plants grown at 12°C the critical CO 2 concentration was 13.35 mmol at 5° C and 21.92 mmol at 10° C. Stimulation by O 2 depended also on the growth temperature: for measurements at 26.31 mmol m −3 CO 2 , O 2 was stimulating at temperatures less than 12°C for plants grown at 12°C and less than 19°C for plants grown at 27°C. The efficiency of the O 2 ‐dependent stimulation of net photosynthesis was maximum at 9.21 mol m −3 O 2 at 26.31 mmol m −3 CO 2 . Oxygen‐stimulation of net photosynthesis was detected in Nicotiana tabacum L. var Samsun, Lycopersicum esculentum L. and Chenopodium album L. At 5°C and under high photon fluence rate, O 2 increased the carboxylation capacity of the photosynthetic apparatus of mustard and decreased its affinity for CO 2 . The O 2 inhibition of the net CO 2 uptake observed at low CO 2 concentrations was the result of a decrease in the affinity for carbon dioxide. The nature of the mechanism which causes the stimulation of photosynthesis is discussed.