PARENT SESSION
Oral Session #106: Plant Ecology: Global Climate Change.
Presiding: D. Breshears
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom East, Radisson.
The effects of solar UV-B on growth and phenylpropanoids of Deschampsia antarctica.
Ruhland, Christopher*,1,2, Xiong, Fusheng2, Clark, W. Dennis2, Day, Thomas2, 1 Minnesota State University, Mankato, MN2 Arizona State University, Tempe, AZ
ABSTRACT- We examined the influence of solar ultraviolet-B radiation (280-315 nm) on performance of Deschampsia antarctica during the 1998-1999 ozone depletion season near Palmer Station, along the Antarctic Peninsula. Treatments involved placing filters on frames over potted plants that either transmitted ("near-ambient UV-B") or absorbed ("reduced UV-B") most biologically effective UV-B. We made non-destructive growth measurements over the course of the experiment and subsequently harvested plants at the end of the ozone depletion season in early 1999. We examined UV-B effects on net and relative growth rates, biomass production and concentrations of UV-B-absorbing soluble and insoluble phenylpropanoids. Plants growing under near-ambient UV-B produced significantly less aboveground biomass and had lower relative growth rates than those under reduced UV-B. These reductions appeared primarily due to lower leaf elongation rates resulting in less total leaf area per plant under the near-ambient UV-B. Caffeic, p-coumaric and ferulic acid were the major hydroxycinnamic acids and luteolin derivatives were the major flavonoids in both soluble and insoluble leaf extracts. Concentrations of insoluble p-coumaric and caffeic acid and soluble ferulic acid were significantly higher under near-ambient UV-B than reduced UV-B. Our results indicate that ambient levels of UV-B during the ozone depletion season along the Antarctic Peninsula reduce growth and biomass production and leads to higher concentrations of hydroxycinnamic acids but not flavonoids in Deschampsia antarctica .
KEY WORDS: Deschampsia antarctica, ozone depletion , ultraviolet-B, Antarctica