ULTRAVIOLET ACTION SPECTRA (280 to 380 nm) AND SOLAR EFFECTIVENESS SPECTRA FOR HIGHER PLANTS

Several ultraviolet (UV) action spectra that typify the responses of higher plants to irradiation by wavelengths between 280 nm and 380 nm are shown. An attempt is made to generate common spectra that may be used, at least temporarily, to represent the effects of UV on such important biological parameters as photosynthesis. The goal is to provide an estimate of plant response to solar UV and to the potential increase in ground level UV postulated for a depleted stratospheric ozone layer. Solar plant damage effectiveness curves are generated under "normal" solar UV conditions, and under an assumed UV increase corresponding to a 16% depletion in total ozone. Additional effects due to ozone depletion are concentrated in the UV-B region, especially at wavelengths between about 297 nm and 315 nm. Common features of these effectiveness curves are noted, and limitations are pointed out. As expected, no common spectrum has been found that can substitute for any specific spectrum nor that is unique enough to provide more than a limited first approximation of a plant damage spectrum. Additional information must be generated to fulfill this need.