Artikel,
Long-term growth of soybean at elevated CO2 does not cause acclimation of stomatal conductance under fully open-air conditions.
Plant, cell & environment, 29 (9): 1794--1800 (September 2006)
DOI: 10.1111/j.1365-3040.2006.01556.x
Zusammenfassung
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 micromol mol(-1)) and elevated CO(2) (552 micromol 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).
