Interactions between ozone and plant cuticles

SUMMARY The flux of ozone to plant surfaces results in its decomposition at the surface and its uptake through the cuticle. Ozone deposition velocity and ozone permeance were determined for a variety of isolated plant cuticles. Ozone deposition velocity was lower than determined with whole plants kept in darkness. It declined continuously during exposure to the gas and showed a‘recovery’effect after an interruption of the fumigation. It increased with the moisture content of the cuticles and decreased when the ozone concentration in the surrounding air was raised. The deposition velocity was much higher than cuticular ozone permeance at equivalent ozone concentrations. Due to the ozone decay in the cuticle, ozone permeance was much lower in thick than in thin cuticles. Even with the most permeable cuticles, ozone uptake under natural conditions is smaller than the flux through open stomata by a factor of at least 10000.