Leaf Stomatal Conductance and Photosynthesis of Field-grown Maize Exposed to Changing Ozone Concentrations

The impacts of moderate ozone levels on leaf conductance and photosynthesis of maize were assessed from field fumigation experiments carried out at Grignon (France) in july-august 2011. The exposition of the plants to ozone was achieved by a linear fumigation device. Continuous measurements of ozone concentration were taken inside the vegetation, close to the ears. The mean daylight ozone levels ranged from 31 ppb (control) to 59 ppb. Although photosynthesis was significantly affected by long-term ozone exposure, stomatal conductance appeared to be moderately sensitive to this pollutant. Furthermore, grain yields were very slightly impacted. A Jarvis-type model of stomatal conductance was used in order to establish an empirical relationship between stomatal uptake of ozone and photosynthetic capacity