We examined the relationships between O₃ sorption and the acute effects of the O₃ on sunflower leaves, such as changes in stomatal response and visible injury, using an image instrumentation method. The results obtained were as follows:
1) Changes in stomatal response to O₃ varied randomly at different sites on a leaf, and were not dependent on the integrated O₃ sorption at these sites. This result suggests that there are differences in stomatal sensitivity to O₃ among local sites on a leaf.
2) The degree of visible injury at local sites on a leaf, which reached chlorosis and necrosis, was not related to the integrated O₃ sorption at these sites. This result suggests that the differences in the degree of the visible injury among local sites on a leaf are dependent on differences not only in factors related to O₃ sorption, but also in other physiological factors among these sites.