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Long‐term growth of soybean at elevated [CO 2 ] does not cause acclimation of stomatal conductance under fully open‐air conditions
Author(s) -
LEAKEY ANDREW D. B.,
BERNACCHI CARL J.,
ORT DONALD R.,
LONG STEPHEN P.
Publication year - 2006
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.1365-3040.2006.01556.x
Subject(s) - stomatal conductance , acclimatization , photosynthesis , stomatal density , conductance , botany , horticulture , chemistry , biology , physics , condensed matter physics
Accurately predicting plant function and global biogeochemical cycles later in this century will be complicated if stomatal conductance ( g s ) acclimates to growth at elevated [CO 2 ], in the sense of a long‐term alteration of the response of g s to [CO 2 ], humidity ( h ) and/or photosynthetic rate ( A ). If so, photosynthetic and stomatal models will require parameterization at each growth [CO 2 ] of interest. Photosynthetic acclimation to long‐term growth at elevated [CO 2 ] occurs frequently. Acclimation of g s has rarely been examined, even though stomatal density commonly changes with growth [CO 2 ]. Soybean was grown under field conditions at ambient [CO 2 ] (378 µ mol mol −1 ) and elevated [CO 2 ] (552 µ mol mol −1 ) using free‐air [CO 2 ] enrichment (FACE). This study tested for stomatal acclimation by parameterizing and validating the widely used Ball et al . model (1987, Progress in Photosynthesis Research, vol IV, 221–224) with measurements of leaf gas exchange. The dependence of g s on A , h and [CO 2 ] at the leaf surface was unaltered by long‐term growth at elevated [CO 2 ]. This suggests that the commonly observed decrease in g s under elevated [CO 2 ] is due entirely to the direct instantaneous effect of [CO 2 ] on g s and that there is no longer‐term acclimation of g s independent of photosynthetic acclimation. The model accurately predicted g s for soybean growing under ambient and elevated [CO 2 ] in the field. Model parameters under ambient and elevated [CO 2 ] were indistinguishable, demonstrating that stomatal function under ambient and elevated [CO 2 ] could be modelled without the need for parameterization at each growth [CO 2 ].