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Plant Responses to Current Solar Ultraviolet‐B Radiation and to Supplemented Solar Ultraviolet‐B Radiation Simulating Ozone Depletion: An Experimental Comparison ¶
Author(s) -
Rousseaux M. Cecilia,
Flint Stephan D.,
Searles Peter S.,
Caldwell Martyn M.
Publication year - 2004
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2004.tb00075.x
Subject(s) - ozone depletion , ultraviolet , ultraviolet b radiation , ozone , sunlight , radiation , ultraviolet b , chemistry , ultraviolet radiation , materials science , physics , optoelectronics , optics , radiochemistry , medicine , organic chemistry , dermatology
ABSTRACT Field experiments assessing UV‐B effects on plants have been conducted using two contrasting techniques: supplementation of solar UV‐B with radiation from fluorescent UV lamps and the exclusion of solar UV‐B with filters. We compared these two approaches by growing lettuce and oat simultaneously under three conditions: UV‐B exclusion, near‐ambient UV‐B (control) and UV‐B supplementation (simulating a 30% ozone depletion). This permitted computation of “solar UV‐B” and “supplemental UV‐B” effects. Microclimate and photosynthetically active radiation were the same under the two treatments and the control. Excluding UV‐B changed total UV‐B radiation more than did supplementing UV‐B, but the UV‐B supplementation contained more “biologically effective” shortwave radiation. For oat, solar UV‐B had a greater effect than supplemental UV‐B on main shoot leaf area and main shoot mass, but supplemental UV‐B had a greater effect on leaf and tiller number and UV‐B‐absorbing compounds. For lettuce, growth and stomatal density generally responded similarly to both solar UV‐B and supplemented UV‐B radiation, but UV‐absorbing compounds responded more to supplemental UV‐B, as in oat. Because of the marked spectral differences between the techniques, experiments using UV‐B exclusion are most suited to assessing effects of present‐day UV‐B radiation, whereas UV‐B supplementation experiments are most appropriate for addressing the ozone depletion issue.