THE IMPACT OF ELEVATED UV-B (280-320 NM) RADIATION-LEVELS ON THE REPRODUCTION BIOLOGY OF A HIGHLAND AND A LOWLAND POPULATION OF SILENE VULGARIS

A highland (altitude 1600 m) and a lowland (altitude -2 m) population of the perennial herb Silene vulgaris were tested on the effects of el evated levels of UV-B radiation on their reproductivity. Highland popu lations receive higher natural UV-B doses than lowland populations. Th erefore adaptation to high W-B levels of the highland population is to be expected. The lowland population showed a decrease in the number o f seed producing flowers and the number of seeds produced per plant un der elevated UV-B levels. The highland population increased the number of seeds per plant under elevated UV-B levels. In both populations in dividual seed mass as well as seed germination percentages were unaffe cted by the UV-B flux received by the parental plant. Possible effects of UV-B induced alterations in reproductivity on the geographical dis tribution of the different populations are discussed.