12 September 2005 Are plants grown under low visible irradiance sensitive to low levels of ultraviolet-B radiation?
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A critical question in ultraviolet-B radiation research is how different portions of the solar spectrum influence plant UV B sensitivity. Field-grown plants show only subtle responses to supplemental UV-B radiation in many aspects of growth, yet plants grown under low visible light (as in most growth chambers and greenhouses) show much more discernible changes. Here we assess a specific aspect of UV-B sensitivity in plants grown under lower PAR: when one maintains a constant proportion of UV-B to PAR, but different absolute irradiance levels, does plant sensitivity to UV-B change? We conducted field experiments at near-ambient PAR and enhanced UV-B, and also with reduced irradiance in both wavebands, on three species. Each of these species occurs in both open and shaded habitats. We found the grass Setaria viridis sensitive to UV-B radiation only when grown at lower irradiances, while the forb Geranium viscosissimum was only sensitive to UV-B at the higher irradiances. In the grass Elymus glaucus, UV-B sensitivity did not appear to be influenced by the irradiance levels. Species appear to respond differently to these changes in irradiance levels, and an array of physiological and anatomical mechanisms are likely involved.
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Stephan D. Flint, Stephan D. Flint, Martyn M. Caldwell, Martyn M. Caldwell, Ron J. Ryel, Ron J. Ryel, "Are plants grown under low visible irradiance sensitive to low levels of ultraviolet-B radiation?", Proc. SPIE 5886, Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, 58860J (12 September 2005); doi: 10.1117/12.615068; https://doi.org/10.1117/12.615068

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