Description:
Among abiotic stressors, drought and enhanced UV radiation (UV) received a lot of attention, because of their potential to impair plant growth. Since drought and UV induce partially similar protective mechanisms, we tested the hypothesis that UV ameliorates the effect of water deficit (WD) in selected grass ( Holcus mollis and Agrostis capillaris ) and herb species ( Hypericum maculatum and Rumex obtusifolius ). During 2011–2014, an outdoor manipulation experiment was conducted on the grassland ecosystem under mountainous conditions (Beskydy Mts; Czech Republic). Lamellar roofs were used to pass or exclude incident precipitation. In addition, the lamellas were made from acrylics either transmitting or blocking incident UV. Generally, both UV exposure and WD enhanced the accumulation of flavonols, while exposure to both factors resulted in additive or less than additive interactions. While UV stimulated an accumulation of flavonols in A. capillaris, H. mollis and H. maculatum , WD increased flavonols in R. obtusifolius . However, the UV-induced acclimation did not mitigate the negative effects of WD on CO 2 assimilation rate and subsequently morphological parameters. The study contributes to better understanding of plant responses to complex environmental conditions and will help for successful modelling forecasts of future climate change impacts