The influence of enhanced UV-B radiation on the spring geophyte Pulmonariaofficinalis

Pulmonaria officinalis is an understorey spring geophyte, which starts its vegetative period before full foliation of the tree storey. During its earl y growth phase it is exposed to full solar radiation, therefore the enhance d UV-B radiation could present a threat to this species. An outdoor experim ent in which potted plants were exposed to below ambient, ambient, and abov e ambient (corresponding to 17% ozone reduction) UV-B radiation, was conduc ted in order to evaluate the radiation effects. The amount of photosyntheti c pigments and photochemical efficiency of PSII were not affected, but the amount of UV-B absorbing compounds was lower in plants grown under reduced UV-B. This change was measurable after only fourteen days in reproductive s hoots, while in the vegetative shoots, it was not detectable until after th ree months. The leaves of P. officinalis are variegated and the light green spots became less transparent to PAR under enhanced UV-B. The results reve al that under simulated 17% ozone depletion the harmful effects of UV-B on the measured parameters were negligible.