Abstract

Chlorofluorocarbons are mainly responsible for the depletion of stratospheric ozone layer which results in increase of UV-B radiation on earth’s environment and causing adverse effects on flora. In the present study we have investigated the effect of ultraviolet-B (UV-B) radiation on two cryptogamic plants (Xanthoria elegans and Bryum argenteum) growing at high altitude of central Himalayan region of India. These plants were naturally receiving UV-B radiation and were analyzed for photosynthetic pigments, UV-B absorbing compounds and phenolics. In the field experiments, both of these plants contain higher amounts of UV-B absorbing compounds and phenolics and no major changes in total chlorophyll and carotenoid under UV-B exposed conditions were recorded. B. argenteum contains higher amounts of total chlorophyll, carotenoids, UV-B absorbing compounds and phenolics than the X. elegans at the duration of 120 h. The maximum average UV-B irradiance was 4.38 Minimal Erythemal Dose per hour (MED/ h) at the experimental site while minimum average UV-B irradiance was 1.72 MED/ h. The UV-B absorbing compounds and phenolics provide protection to these plants against UV-B radiation.

Key words: Total chlorophyll, high altitude, pigments, UV-B absorbing compounds, UV-B radiation