sodininkystė ir daržininkystė 25(4)

Discussion. Plants in equatorial and high-altitude regions of the earth, where
UV-B flux is generally higher, demonstrate the capacity of increased UV-B tolerance
by inducible flavonoid production. The species found at low latitudes also include
temperate latitude species that have been introduced into these regions such as Pisum
sativum further demonstrating the capacity for photobiological adaptation (Cockell
and Knowland, 1999). As the UV-B doses in low-latitude are greater by an order of
magnitude than those existing in high-latitude areas, these ranges provide certain
evidence of the plant acclimation capacity due to change of UV screening compounds
composition. However, a linear relationship between concentration of UV
absorbing compounds and UV-B daily doses has not been observed in this study.
Moreover, content of UV screening compounds appeared to be more determined by
stressors such as an increased temperature and CO 2
level rather than an intensity of
exposure to UV-B radiation. Therefore, it is most likely that certain plant systems
identify increased temperature and CO 2
level as the fact of a latitude lowering. According
to Urbonavièiûtë et al. (2006) content of certain flavonoids is determined
even by a spatial plant leaf orientation. Such data proposes an idea of interaction
between photomorphological and photosynthetic system in order to foresee and prevent
probable UV-B damage.
Conclusions. In general, plant’s response to UV-B exposure intensity is very
species-specific under UV-B stress. However, content of UV screening compounds
appeared to be more determined by the stressors such as an increased temperature
and CO 2
level rather than an intensity of exposure to UV-B radiation.
Acknowledgement. Authors are grateful to Lithuanian State Science and Studies
Foundation for research support.
Gauta 2006-11-10
Parengta spausdinti 2006-12-11
References
1. Barnes P. W., Jordan P. W., Gold W. G., Flint S. D., Caldwell M. M. Competition,
morphology and canopy structure in wheat (Triticum aestivum L.) and wild oat (Avena
fatua L.) exposed to enhanced ultraviolet-B radiation // Functional Ecology. 1988. Vol. 2.
P. 319–330.
2. Cockell C. S., Knowland J. Ultraviolet radiation screening compounds // Biology
Reviews. 1999. Vol. 74. P. 311–345.
3. Flint S. D., Caldwell M. M. Influence of floral properties on the ultraviolet radiation
environment of pollen // American Journal of Botany. 1983. Vol. 70. P. 1416–1419.
4. Harborne J. B. Biochemistry of phenolic compounds. Academic Press,
London, 1964.
5. Harm W. Biological effect of ultraviolet radiation. IUPAB biophysics series I.
Cambridge University Press, Cambridge, 1980.
6. Mirecki R. M., Teramura A. H. Effects of ultraviolet-B irradiance on soybean. V.
The dependence of plant sensitivity on the photosynthetic photon flux density during
and after leaf expansion // Plant Physiology. Vol. 74. 1984. P. 475–480.
7. Mohle B., Wellman E. Introduction of phenylpropanoid compounds by UV-B
irradiation in roots of seedlings and cell cultures from Dill (Anethum gaveolens L.) // Plant
Cell Reports. 1982. Vol. 1. P. 183–185.
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