Stomatal responses to raised atmospheric CO2 concentrations during exposure of plants to SO2 pollution
Abstract Stomata provide the main routes for entry of pollutants into the leaves of higher plants, and it has been suggested that inhibitors of stomatal opening could be used to protect plants against pollution. Experimental evidence is presented indicating that the stomatal closing response to CO 2 still occurs in the presence of SO 2 , even in conditions in which SO 2 alone stimulates stomatal opening. The increases in CO 2 concentration that occur in polluted atmospheres appear to be sufficient to cause partial stomatal closure. The variability between individual plants in the magnitude of the stomatal response to CO 2 is considerable, and the response could be one useful criterion to employ for selection purposes when crop varieties are produced for growing in polluted areas.