Stomata are less responsive to environmental stimuli in high background ozone in Dactylis glomerata and Ranunculus acris.
Two mesotrophic grassland species, Ranunculus acris and Dactylis glomerata were exposed to a range of ozone treatments (16.2-89.5 ppb 24 h mean) and two watering regimes under naturally fluctuating photosynthetically active radiation (PAR), vapour pressure deficit (VPD) and temperature. Stomatal conductance was measured throughout the experiments, and the combined data set (>1000 measurements) was analysed for effects of low and high ozone on responses to environmental stimuli. We show that when D. glomerata and R. acris were grown in 72.6-89.5 ppb ozone the stomata consistently lose the ability to respond, or have reduced response, to naturally fluctuating environmental conditions in comparison to their response in low ozone. The maximum stomatal conductance (g(max)) was also significantly higher in the high ozone treatment for D. glomerata. We discuss the hypotheses for the reduced sensitivity of stomatal closure to a changing environment and the associated implications for ozone flux modelling.
Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK. sergga@ceh.ac.uk
Serena
S
Wagg
Gina
G
Mills
Felicity
F
Hayes
Sally
S
Wilkinson
William J
WJ
Davies
D000393:Air Pollutants / Q000633:toxicity*; D055907:Climatic Processes; D031745:Dactylis / Q000187:drug effects* / Q000502:physiology; D010126:Ozone / Q000633:toxicity*; D054046:Plant Stomata / Q000187:drug effects* / Q000502:physiology; D031947:Ranunculus / Q000187:drug effects* / Q000502:physiology; D055548:Vapor Pressure
D000393:Air Pollutants; D010126:Ozone