Epidermal screening of UV-B radiation in loblolly pine and sweetgum
- West Virginia Univ., Morgantown, WV (United States); and others
Seedlings of loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) were grown in a greenhouse at the University of Maryland under either no UV-B radiation or daily supplemental UV-B radiation levels of 4, 8 or 11 kJ m{sup -2} of Biologically Effective. UV-B radiation. Measurements of leaf elongation, plant growth and UV-absorbing pigments were made and, at the conclusion of the growing season, measurements of UV-B screening effectiveness in different leaf age classes were made with a fiber-optic microprobe. In loblolly pine, less than 0.5 % of incident UV-B radiation was transmitted through the epidermis of fascicle needles and transmittance was less in needles that received UV-B radiation. Increases in epidermal thickness and the concentration of UV-absorbing corn may have accounted for this low transmittance. Transmission was slightly greater (about 1%) in primary needles, possibly due to a thinner epidermis. In contrast, in sweetgum, epidermal transmittance ranged from about 20% in leaves not preconditioned to UV-B exposure, to about 12% in leaves grown under UV-B radiation. These results suggest that any deleterious effects of UV-B radiation may be anticipated to be greatest in early stages of leaf development and in primary needles of conifers, before UV-B penetration is reduced by increases in epidermal thickness and UV-absorbing compounds.
- OSTI ID:
- 95808
- Report Number(s):
- CONF-9507129-; ISSN 0012-9623; TRN: 95:004728-0073
- Journal Information:
- Bulletin of the Ecological Society of America, Vol. 76, Issue 2; Conference: 80. anniversary of the transdisciplinary nature of ecology, Snowbird, UT (United States), 30 Jul - 3 Aug 1995; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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