Oak (Quercus robur L.) seedlings responses to a realistic increase in UV-B radiation under open space conditions

Plants show different levels of sensitivity to ultraviolet-B (UV-B) radiation and acclimation to high UV-B irradiances had been developed in many species. A field experiment was performed during 1995 to study the adaptative responses of oak plants (Quercus robur L.) to artificial UV-B supplementation. The most important effect of UV treatment was the increase in lear thickness and the accumulation of phenolic compounds in the secondary wall of the adaxial epidermis of leaves in UV treated plants; the secondary wall of cells in the abaxial epidermis, that is not directly exposed to supplemental UV-B, did not present any alterations. No effects were observed on photosynthesis, while plant morphology was sensible to UV treatment. (C) 1998 Elsevier Science Ltd.