Effects of UV-B radiation on Olea europaea: comparisons between a greenhouse and a field experiment.

We compared growth, morphology, anatomy and physiology of field-grown Olea europaea L. plants after one year with or without supplemental UV-B radiation equivalent to the increase at ground level resulting from a 15% depletion in stratospheric ozone concentration over Patras, Greece (38.3 degrees N, 29.1 degrees E). In a parallel greenhouse experiment, plants were exposed for four months to either zero UV-B radiation or UV-B radiation equivalent to that of the supplemented outdoor treatment. In the field, the only significant changes in response to supplemental UV-B radiation were an increase in adaxial epidermal thickness and a decrease in total protein concentration. In the greenhouse-grown plants, UV-B radiation caused significant increases in abaxial cuticle thickness and trichome UV-B absorbing compounds. We conclude that Olea europaea exhibits high UV-B tolerance and will not be affected by the predicted increases in UV-B radiation.