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Elevated CO 2 and ozone reduce nitrogen acquisition by Pinus halepensis from its mycorrhizal symbiont
Author(s) -
Kytöviita MinnaMaarit,
Le Thiec Didier,
Dizengremel Pierre
Publication year - 2001
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2001.1110307.x
Subject(s) - photosynthesis , ozone , paxillus involutus , shoot , symbiosis , botany , nutrient , nitrogen , assimilation (phonology) , ectomycorrhiza , horticulture , biology , mycorrhiza , chemistry , ecology , linguistics , genetics , philosophy , organic chemistry , bacteria
The effects of 700 μmol mol −1 CO 2 and 200 nmol mol −1 ozone on photosynthesis in Pinus halepensis seedlings and on N translocation from its mycorrhizal symbiont, Paxillus involutus, were studied under nutrient‐poor conditions. After 79 days of exposure, ozone reduced and elevated CO 2 increased net assimilation rate. However, the effect was dependent on daily accumulated exposure. No statistically significant differences in total plant mass accumulation were observed, although ozone‐treated plants tended to be smaller. Changes in atmospheric gas concentrations induced changes in allocation of resources: under elevated ozone, shoots showed high priority over roots and had significantly elevated N concentrations. As a result of different shoot N concentration and net carbon assimilation rates, photosynthetic N use efficiency was significantly increased under elevated CO 2 and decreased under ozone. The differences in photosynthesis were mirrored in the growth of the fungus in symbiosis with the pine seedlings. However, exposure to CO 2 and ozone both reduced the symbiosis‐mediated N uptake. The results suggest an increased carbon cost of symbiosis‐mediated N uptake under elevated CO 2 , while under ozone, plant N acquisition is preferentially shifted towards increased root uptake.