||Plant Protective Response to Enhanced UV-B Radiation under Field Conditions: Leaf Optical Properties and Photosynthesis.
Flint, S. D. ;
Jordan, P. W. ;
Caldwell, M. M. ;
||Utah State Univ., Logan.;Corvallis Environmental Research Lab., OR.
Ultraviolet radiation ;
Plant growth ;
Damage assessment ;
Plant tissues ;
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Plants of Vicia faba were grown in the field during the early to midsummer while receiving two levels of supplemental UV-B radiation. Light-saturated photosynthesis and stomatal diffusive conductance of intact leaves did not show any indications of UV-radiation damage. Supplemental UV treatment did cause increased concentrations of UV-absorbing flavoid pigments in leaf tissues and decreased epidermal transmittance of UV radiation. While epidermal transmittance was reduced 30% under the low-UV treatment, the high-UV treatment failed to elicit as large a change. However, total amounts of flavonoids in other leaf tissues did increase in response to the high-UV treatment (up to 12% greater per unit leaf area than for control plants). This may have been a major factor protecting underlying photosynthetic tissues. (Copyright (c) 1985 Pergamon Press Ltd.)