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Changes in net photosynthesis and growth of Pinus eldarica seedlings in response to atmospheric CO 2 enrichment
Author(s) -
GARCIA R. L.,
IDSO S. B.,
WALL G. W.,
KIMBALL B. A.
Publication year - 1994
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/j.1365-3040.1994.tb00326.x
Subject(s) - photosynthesis , seedling , environmental science , atmospheric sciences , botany , pinus <genus> , carbon dioxide , horticulture , primary production , chemistry , ecology , biology , physics , ecosystem
Pinus eldarica L. trees, rooted in the natural soil of an agricultural field at Phoenix, Arizona, were grown from the seedling stage in clear‐plastic‐wall open‐top enclosures maintained at four different atmospheric CO 2 concentrations for 15 months. Light response functions were determined for one tree from each treatment by means of whole‐tree net CO 2 exchange measurements at the end of this period, after which rates of carbon assimilation of an ambient‐treatment tree were measured across a range of atmospheric CO 2 concentrations. The first of these data sets incorporates the consequences of both the CO 2 ‐induced enhancement of net photosynthesis per unit needle area and the CO 2 ‐induced enhancement of needle area itself (due primarily to the production of more needles), whereas the second data set reflects only the first of these effects. Hence the division of the normalized results of the first data set by the normalized results of the second set yields a representation of the increase in whole‐tree net photosynthesis due to enhanced needle production caused by atmospheric CO 2 enrichment. In the solitary trees we studied, the relative contribution of this effect increased rapidly with the CO 2 concentration of the air to increase whole‐tree net photosynthesis by nearly 50% at a CO 2 concentration approximately 300 μmol mol −1 above ambient.