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

The impacts of moderate oz one levels on leaf conduct ance and photosynthesis of maize were assessed from field fumigation expe riments carried out at Grignon (France) in july-august 2011. The expo sition of the plants to ozone was achieved by a linear fumigation device. Continuous measurements of ozone concentration were taken inside th e vegetation, close to the ears. The mean daylight ozone le vels ranged from 31 ppb (control) to 59 ppb. Although photosynthesi s was significantly affected by long-term oz one exposure, stomatal conductance appear ed to be moderately sensitive to this pollutant . Furthermore, grain yields were very slightly impa cted. A Jarvis-type model of stomatal conductance was used in order to establish an empirical relationship between stomatal uptake of ozone and photosynthetic capacity