Figure 2.
Effects of ozone on net photosynthesis rate (Pn) and stomatal conductance (gs). Measurements were made on the fourth fully expanded leaves of ozone-tolerant clone 245 plants or ozone-sensitive clone 388 plants after 2 and 4 d of exposure to ambient air or a 6-h daily treatment with 300 ppb ozone. Bars represent the mean of eight plants ±se. Results of analysis of variance produced the following P values for photosynthesis (ozone = 0.0035, clone = 0.7058, day = 0.0036, ozone × clone = 0.1477, ozone × day = 0.0081, and clone × day = 0.7137) and stomatal conductance (ozone = 0.0150, clone = 0.0906, day = 0.0001, ozone × clone = 0.0002, ozone × day = 0.0001, and clone × day = 0.0026).