Chlorophyll fluorescence assay for ozone injury in intact plants

A chlorophyll fluorescence induction (Kautsky effect) assay predicted ozone-induced injury in bean leaves (Phaseolus vulgaris) at least 20 hours before any visible sign of leaf necrosis. The extent of injury, which could be predicted during exposure to ozone, depended on concentration, exposure time, and leaf development stage. Much more injury occurred in light than in darkness and long exposures to lower ozone concentrations were more injurious than brief exposures to higher ones. The first detectable effect was on the photosynthetic water-splitting enzyme systems, followed by inhibition of electron transport between the photosystems. The fluorescence assay provides a simple, rapid, nondestructive method for observing effects of ozone on plants.