Acta Silvatica & Lignaria Hungarica 2008 [antikvár]

Acta Silv. Lign. Hung., Vol. 4 (2008) 7-16 Ecophysiological Investigation of UV-B Tolerance of Beech Saplings (Fagus sylvatica L.) Réka láposi* - Szilvia Veres - Ilona mészáros Department of Botany, University of Debrecen, Debrecen, Hungary Abstract - Our work aimed to reveal UV-B sensitivity of beech both in field, and in outdoor conditions. We examined the role of UV-B radiation in activation of photoprotective mechanisms in photoinhibition and photodamage of photosynthetic apparatus under hight light intensity. Our results indicate that under natural irradiances increase of carotenoid content - especially xantophyll cycle pigments - and xantophyll cycle activity resulted in not only by visible light but alsó by UV-B radiation. These pigments have important role in photoprotective processes of photosynthetic apparatus. Amount of these pigments decreased under UV-B exclusion, increased under UV-B exposure, similarly to the UV-B absorbing compounds, which responded susceptibly to changes of UV-B level. These results may suggest that high UV-B tolerance of beech is due to the considerable flavonoid accumulation, which may explain practically unaltered physiological activity of photosynthetic apparatus under UV-B exposition, as these compounds have antioxidant capacity, thus they can reduce lipid peroxidation and damage of photosynthetic apparatus. enhanced UV-B / UV-B exclusion / photosynthetic pigments / chlorophyU fluorescence / UV-B absorbing compounds