Interactions between ozone and plant cuticles: II. Water permeability

Beech (Fagus sytvatica L.) and ivy (Hedera helix L.) plants, as well as isolated cuticles of the adaxial leaf surfaces of Citrus aurantium L., Ficus elastica Roxb. var. decora and Hedera helix L., were exposed to environmentally realistic ozone concentrations (up to 130 nl ⁻¹)in combination with acid fog (pH 3.0) for several months. Isolated Citrus, Ficus and Hedera cuticles and cuticles isolated from adaxial leaf surfaces of Hex aquifolium L. and Prunus laurocerasus L. and from fruits of Capsicum annuum L. and Lycopersicon esculentum Mill, were fumigated with 2.5 % (v/v) ozone for 1 or 2 h in dry and moist conditions, respectively. The water permeance (P) of the non‐isolated cuticles of the astomatous adaxial leaf sides of beech and ivy and of the isolated cuticles was not altered by expositure to a realistic ozone stress. Fumigation with very high ozone concentrations decreased P of isolated Ficus and Hedera cuticles by about 20% and increased P of all other isolated cuticles by up to 200% (Capsicum). In some cases the 2 h fumigation under moist conditions had no significant effect upon P. The different effects are tentatively explained in terms of the structure of the cuticles.