Growth of Sphagnum Riparium Contains the Signature of Short Wavelength UV-B Passing Through the Ozone Layer

It follows from the negative reaction of plant growth to UV-B that the wavelengths penetrating through the ozone layer, in contrast to the absorbed ones, should leave a specific signature in the form of growth inhibition. This signature is expected, for example, for peat mosses of the Sphagnum genus. To test this hypothesis, we studied the growth response of Sphagnum riparium Ångstr. to solar UV in the 200-310 nmrange, recorded outside the Earth’s atmosphere. It was found that wavelengths starting from 286 nm significantly inhibited the growth of Sphagnum, while shorter wavelengths hadno significant effect. It follows that wavelengths starting from 286 nm reach the Earth’s surface, while shorter ones are absorbed by the ozone layer. These data correspond to the physical concepts of the 286 nm limit for solar radiation penetration through the ozone layer. Based on the universal UVR8-dependent mechanism of UV-B reception in plants, we conclude that plants have potential as indicators for assessing the penetration of the shortest solar UV-B wavelengths through the ozone layer. Keywords: UV-B, 286 nm, Sphagnum, growing season, growth inhibition