sodininkystė ir daržininkystė 25(4)

SCIENTIFIC WORKS OF THE LITHUANIAN INSTITUTE OF
HORTICULTURE AND LITHUANIAN UNIVERSITY OF AGRICULTURE.
SODININKYSTË IR DARÞININKYSTË. 2006. 25(4).
VARIABILITY OF UV-ABSORBING COMPOUNDS IN
PLANT LEAVES UNDER UV-B EXPOSURE
Kæstutis BARANAUSKIS, Jurga SAKALAUSKAITË,
Auðra BRAZAITYTË, Akvilë URBONAVIÈIÛTË,
Giedrë SAMUOLIENË, Gintarë ÐABAJEVIENË,
Sandra SAKALAUSKIENË, Jûratë Bronë ÐIKÐNIANIENË,
Pavelas DUCHOVSKIS
Lithuanian Institute of Horticulture, LT–54333 Babtai, Kauno 30,
Kaunas distr., Lithuania.
E-mail k.baranauskis@lsdi.lt
Variability of UV-absorbing compounds in leaves of Daucus sativus Röhl., Fragaria
ananassa Duch. Malus domestica and Raphanus sativus L. under different UV-
B exposure was examined. Effect of an additional stress including increased temperature
(25°C-day/16°C-night) and CO 2
level (700 ppm) on UV-screening compound in
Malus domestica and Raphanus sativus L. leaves was identified as well. In general,
this study revealed that plant response to UV-B exposure intensity is very speciesspecific
only under non-stressful conditions; i. e. favorable temperature and ambient
CO 2
level, though a linear relationship between concentration of UV-absorbing compounds
and UV-B daily doses has not been determined. Content of UV-screening
compounds appeared to be more determined by stressors including an increased
temperature and CO 2
level rather than an intensity of exposure to UV-B radiation.
Key words: Daucus sativus Röhl., Fragaria ananassa Duch. Malus domestica,
Raphanus sativus L., UV-absorbing compounds, UV-B radiation.
Introduction. Plants use sunlight for photosynthesis and, as a consequence,
are exposed to the ultraviolet (UV) radiation that is present in direct sunlight. All
types of UV radiation, especially the higher energy wavelengths are known to disorder
various plant processes. Such disturbances include DNA damage (Harm, 1980),
inhibition of photosynthetic primary productivity (Tevini and Teramura, 1989), inhibition
of nitrogenase activity (Sinha et al., 1996), and a diversity of other responses
that have been reviewed elsewhere (Tevini, 1993; Vincent and Roy, 1993). However,
it is wrong to consider UV radiation as only damaging factor. It has certain beneficial
roles in the biosphere. As an example, various growth and photomorphogenetic effects
in plants, mediated through blue/UV-A receptors, involve UV-A radiation (Salisbury
and Ross, 1992). Even UV-A reflected from petal anthocyanins is essential
for flower recognition by pollinating insects (Flint and Caldwell, 1983).
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