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Proceedings Paper

Effects of UV-B radiation on phenolic composition and deposition patterns and leaf physiology in three Eastern tree species
Author(s): Joseph H. Sullivan; Dennis C. Gitz; Michael S. Peek; Andrew J. McElrone
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Paper Abstract

Quantitative changes in foliar chemistry in response to UVB radiation are frequently reported but less is known about the qualitative changes in putative UV-screening compounds. It has also not been conclusively shown whether qualitative differences in screening compounds or differences in localization patterns influences the sensitivity of plants to damage from UVB radiation. In this study we evaluated the chemical composition and deposition patterns of UV-absorbing compounds in three tree species and assayed these species for possible effects on gas exchange and photosynthetic carbon assimilation. Branches of mature trees of sweetgum (Liquidambar styraciflua), tulip poplar (Liriodendron tulipifera) and red maple (Acer rubrum) were exposed to supplemental levels of UVB radiation over three growing seasons. Controls for UVA were also measured by exposing branches to supplemental UVA only, and additional branches not irradiated were also used for controls. These species demonstrated contrasting chemical composition and deposition patterns with poplar being the most responsive in terms of epidermal accumulation of phenolics including flavonols and chlorogenic acid and hydroxycinnamates. Sweetgum and red maple showed increases primarily in hydroxycinnamates, particularly in the mesophyll in red maple. Leaf area was marginally influenced by UV exposure level. Assimilation was generally not reduced by UVB radiation in these species and was enhanced in red maple by both UVB and UVA and by UVA in sweetgum. These finding are consistent with a hypothesis that epidermal attenuation of UVB would only be reduced in poplar, which accumulated the additional epidermal screening compounds. It is possible that photosynthetic efficiency was enhanced in red maple by the increased absorption of blue light within the mesophyll. Stomatal conductance was generally reduced, and this led to an increase in water use efficiency in red maple and poplar.

Paper Details

Date Published: 17 January 2002
PDF: 13 pages
Proc. SPIE 4482, Ultraviolet Ground- and Space-based Measurements, Models, and Effects, (17 January 2002);
Show Author Affiliations
Joseph H. Sullivan, Univ. of Maryland/College Park (United States)
Dennis C. Gitz, Univ. of Maryland/College Park (United States)
Michael S. Peek, Univ. of Maryland/College Park (United States)
Andrew J. McElrone, Univ. of Maryland/College Park (United States)

Published in SPIE Proceedings Vol. 4482:
Ultraviolet Ground- and Space-based Measurements, Models, and Effects
James R. Slusser; Jay R. Herman; Wei Gao, Editor(s)

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