We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the maximum photochemical efficiency of photosystem II (F(v)/F(m)), bulk-soluble phenolic concentrations, ferric-reducing antioxidant power (FRAP) and growth of Avena sativa. Treatments involved placing filters on frames over potted plants that reduced levels of biologically effective UV-B by either 71% (reduced UV...

—Numerous anthropogenic and natural factors affect living organisms in nature. Anthropogenic factors include a wide array of contaminants and processes that alter the habitat on both local and global scales. For example, chlorofluorocarbons (CFCs) and other industrial gases contribute to the depletion of the earth’s protective ozone layer, resulting in increased amounts of cell damaging ultravi...

1 Ultraviolet-B radiation (UV-B, 280-320 nm) was surveyed in a mixed deciduous forest in Maryland, USA, using a Robertson-Berger meter. A smaller number of comparable measurements were made in closed-canopy forests in Chile, Panama, and Washington State, USA, and under two canopies recently disturbed by hurricanes, in Virginia, USA, and Mexico. Simultaneous measurements of photosynthetically ac...

Attenuation of UV-B radiation in the water column occurs due to absorption and scatter but in shallow clear freshwater systems enhanced UV-B radiation might be of importance in affecting aquatic organisms. Two laboratory experiments were performed to determine whether two species of charophytes typical for shallow waterbodies, such as Chara polyacantha and Nitella hyalina, are negatively affect...

An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late se...

Ground levels of solar UV-B radiation induce DNA damage. Sessile phototrophic organisms such as vascular plants are recurrently exposed to sunlight and require UV-B photoreception, flavonols shielding, direct reversal of pyrimidine dimers and nucleotide excision repair for resistance against UV-B radiation. However, the frequency of UV-B-induced mutations is unknown in plants. Here we quantify ...

Ultraviolet-B radiation (UV-B; 280–320 nm) penetrates some aquatic habitats to biologically significant depths and can alter life histories of aquatic organisms, including algae, zooplankton, fish, and amphibians. Although major species differences have been documented for UV-B sensitivity, few studies have examined differences between populations of the same species. Previous work has suggeste...

UV-B Stress, Pigment and Protein Content, Pure Cultures o f Marine D iatom s Several species o f marine diatoms were grown at + 18 °C and + 2 2 °C under normal air condi­ tions (0.035 vol.% C 0 2) at a light/dark alteration o f 14: 8 h. Intensity o f white light was 1 mW (~ 5000 lux). An artifical nutrient solution o f 35%o salinity was used. Algae harvested during exponential growth — were exp...