Effect of Relative Humidity Prior to and during Exposure on Response of Peas to Ozone and Sulfur Dioxide

Abstract

Pea (Pisum sativum L. ‘Alsweet’) plants were grown in a controlled environment and exposed to ozone, sulfur dioxide, or a mixture of the 2 pollutants. Plants were preconditioned with low (36%) or high (77%) relative humidity (RH) for 6 days and then exposed to the pollutants for 2 hr in low (31%) or high (67%) RH. Injury was evaluated as both necrosis and chlorophyll concentrations. A high RH prior to exposure to air pollutants greatly increased subsequent plant injury from pollutants. The increased injury with high RH prior to exposure to pollutants was associated with increased stomatal conductance. Relative humidity during exposure to air pollutants had little effect on plant injury.