The impact of UV-B and sulphur- or copper-containing solutions in acidic conditions on chlorophyll fluorescence in selected Ramalina species.

Abstract: Ramalina maciformis and Ramalina lacera were exposed to different solutions and UV-B to seek for alterations in the PSII photosynthetic quantum yield (F _v/F _m), in response to chemicals and radiation. For R. maciformis, significant alterations of the F _v/F _m ratio occurred only in response to different bisulphite solutions. The F _v/F _m ratio decreased most in R. maciformis and R. lacera following exposure to 5 and 1mM bisulphite, respectively. Significant differences in F _v/F _m ratios were observed for R. lacera in response to different solutions and light at different wavelengths, this being synergistic. The PSII system was unaffected by simulated acid rain in both lichens. R. maciformis, in particular, may survive limited acid rain exposure owing to high Ca oxalate accumulation. The F _v/F _m ratio decreased most in R. lacera following short-term exposures to CuSO₄, suggesting that this species is more sensitive to Cu ions under acidic conditions. [Copyright &y& Elsevier]