National Repository of Grey Literature 11 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Influence of the chlorophylls-to-carotenoids ratio on light use efficiency estimation by optical parameters
Ač, Alexander ; Kováč, Daniel ; Veselovská, Petra ; Večeřová, Kristýna ; Klem, Karel
The influence is examined of changing leaf photosynthetic pigments concentrations on sensitivity of the\nphotochemical reflectance index (PRI) and ΔPRI optical parameters in relation to light use efficiency\n(LUE). Photosynthetic and leaf chlorophylls-to-carotenoids (Chl/Car) ratio changes during the growth of\nEuropean Beech (Fagus sylvatica) and Norway spruce (Picea abies) saplings were induced by altering the\nliving environment inside growth chambers. Point reflectance measurements of each individual tree were\nrecording changes in optical properties while measurements were being taken simultaneously of altering\nphotosynthesis. Based on the evaluation of 45 pairs of measurements conducted on six individual saplings,\nthe observed variability in the strength of the PRI and ΔPRI versus LUE relationships was compared to the\nresulting leaf Chl/Car ratio of each tree. Data were used to explain the influence of changing pigments on\nthe sensitivity of each individual optical parameter with regards to the LUE estimation.
Interactive effect of UV radiation and CO2 treatment on extractable volatile organic compounds from European beech leaves
Večeřová, Kristýna ; Pernicová, N. ; Klem, Karel ; Urban, Otmar
The main objective of this experiment was to investigate the combined effect of different UV treatments\nand elevated CO2 concentration on monoterpene and methyl salicylate (MES) content in leaves of\nEuropean beech during the growing season. Plants were grown under ambient (AC, 400 μmol mol–1) and\nelevated (EC, 700 μmol mol–1) CO2 concentrations and three UV radiation treatments (ambient – UVamb,\nexcluded – UV-, and enhanced – UV+). Leaves collected from July to September were extracted in cold\nheptane to determine volatile organic compounds content using gas chromatography. Our results show\nthat AC plants had higher total content of extractable monoterpenes and MES than did EC plants over\nthe whole growing season and irrespective of UV treatment. Limonene, 2-bornene, and ester MES were\nthe most abundant volatile compounds in beech leaves. The highest contents of 2-bornene and MES were\nfound under the UV- treatment and AC. Contents of α-pinene, β-pinene, and carene decreased during the\ngrowing season while the content of limonene increased.
Dream in the Work of Fyodor Mikhailovich Dostoyevsky
Večeřová, Kristýna ; Kosáková, Hana (advisor) ; Nykl, Hanuš (referee)
This bachelor thesis deals with the motive of dream in the works of Fyodor Mikhailovich Dostoyevsky (1821-1881). The thesis focuses on the relation between dream and reality in the writer's literary fiction. After briefly summarising the approaches of the researchers who have studied the motive in Dostoyevsky's work, the author looks into the way the writer integrates the motive of dream into his literary fiction. Various types of confrontation of dream and reality in Dostoyevsky's prosaic texts are presented and the functions which dreams as a literary device fulfil are introduced. The closing chapter of the thesis regards the motive of dream as part of the artistic- philosophical intent of the writer and proposes a possible interpretation of its role in the achieving this intention.
Combined effect of temperature and CdO nanoparticles treatment on Picea abies
Večeřová, Kristýna ; Mikuška, Pavel ; Oravec, Michal ; Kozáčiková, Michaela ; Pompeiano, Antonio ; Coufalík, Pavel ; Urban, Otmar
Three-years old seedlings of Picea abies were pre-treated under two different\ntemperatures (20x35 °C) and subsequently exposed to elevated concentration of CdO\nnanoparticles (CdONPs). Two-week exposure to airborne CdONPs of ecologically\nrelevant size and concentration significantly reduced photosynthetic light use efficiency\nin plants as well as contents of photosynthetic pigments and saccharides. In contrary,\namino acid content was increased under CdONPs. These changes were further\nmodulated by previous growth temperature.
Elevated temperature stimulates light-induced processes that contribute to protecting photosystem II against oxidative stress
Materová, Z. ; Štroch, Michal ; Holubová, I. ; Sestřenková, J. ; Oravec, Michal ; Večeřová, Kristýna ; Špunda, Vladimír
We focused on elucidating the impact of elevated temperature on rapid induction of zeaxanthin (Z)- dependent photoprotection in two different plant species. The dynamics of violaxanthin (V) de-epoxidation under different illumination regimes was studied together with chlorophyll a fluorescence transients in Picea abies seedlings and Arabidopsis thaliana leaves pre-acclimated to temperatures ranging from 20 to 40°C. Whereas for spruce seedlings the rapid phase of V de-epoxidation (induced by either 10 s illumination or 10 light pulses 1 s in duration at 1 min intervals) was gradually stimulated upon increasing temperatures, for A. thaliana leaves considerable acceleration of V de-epoxidation occurred only at 40°C. Moreover, only for spruce seedlings was a considerable amount of Z accumulated after 10 × 1 s illumination. Elevated temperatures stimulated rapid formation of Z-dependent non-radiative dissipation of excitation energy within photosystem II (NRD) induced by 1 s light pulses only for spruce seedlings. The possible role of a specific fatty acid composition in spruce thylakoid membrane lipids in facilitated V de-epoxidation and NRD induction at elevated temperatures is discussed.
Effects of vegetation season and needles’ position in spruce canopy on emissions of volatile organic compounds
Večeřová, Kristýna ; Holišová, Petra ; Pallozi, E. ; Guidolotti, G. ; Calfapietra, Carlo ; Urban, Otmar
The main objective of this study was to investigate seasonal changes and vertical distribution in emissions of biogenic volatile organic compounds (BVOCs) within a Norway spruce canopy profile. Emissions were measured on current-year needles from the upper and lower canopy in early July and late August. Our results show that total BVOC emissions under standardized conditions (light intensity 1,000 µmol m–2 s–1, temperature 30°C) are higher in July than they are in August. BVOC emissions from upper canopy needles were approximately 3 times higher than were those from lower canopy needles. This difference was observed in July but not in August. The monoterpenes α-pinene, camphene, and terpinolene showed the most significant differences between emissions from upper and lower canopy needles.
Comparison of emissions of biogenic volatile organic compounds from leaves of three tree species
Holišová, Petra ; Večeřová, Kristýna ; Pallozi, E. ; Guidolotti, G. ; Esposito, R. ; Calfapietra, Carlo ; Urban, Otmar
Biogenic volatile organic compounds (BVOCs) play many roles in plants’ ecophysiology and have the potential to affect atmospheric quality due to their chemical reactivity. Rates of BVOC emissions are highly variable depending on plant species and growing condition. Our study evaluated the amounts and spectra of BVOCs emitted from three tree species. We investigated BVOC emissions from the leaves of mature Norway spruce and sessile oak saplings grown in the field and from 1-year-old cuttings of hybrid poplar grown under laboratory conditions. Emitted BVOCs were sampled on desorption Tenax tubes in parallel with gas-exchange measurements. After subsequent thermal desorption of Tenax tubes, BVOC profiles were estimated by gas chromatography coupled with mass spectrometry. The tree species showed substantial differences in BVOC emission rates per unit leaf area ranging between 2.33 and 25.67 nmol m–2 s–1. Spruce trees had the lowest BVOC emissions and oak had slightly higher BVOC emissions on average than did poplar. Isoprene composed more than 97% of total BVOC emissions from oak and poplar, while no isoprene emissions from spruce needles were detected. Spruce BVOC emissions were mainly composed of such monoterpenes as α-pinene, β-pinene, and limonene.
Convergence of morphological, biochemical, and physiological traits of upper and lower canopy of European beech leaves and Norway spruce needles within altitudinal gradients
Rajsnerová, Petra ; Klem, Karel ; Večeřová, Kristýna ; Veselá, Barbora ; Novotná, Kateřina ; Rajsner, Lukáš ; Holub, Petr ; Urban, Otmar
Climatic variation along altitudinal gradients provides an excellent natural experimental set-up for investigating the possible impacts of climate change on terrestrial organisms and ecosystems. The present work has explored for the first time the acclimation of upper versus lower canopy leaves or needles in European beech (Fagus sylvatica) and Norway spruce (Picea abies) forests along an altitudinal gradient. We tested the hypothesis that restrictive climatic conditions associated with high altitudes reduce within-canopy variations of leaf traits. The investigated beech and spruce forests were located on the southern slope of the Hrubý Jeseník Mountains (Czech Republic). All measurements were taken on leaves from the upper and lower parts of the canopy of mature trees (>60 years old) growing at low (400 m a.s.l.), middle (720 m a.s.l.), and high (1,100 m a.s.l.) altitudes. Generally, we observed that with increasing altitude, which is associated with adverse microclimatic conditions, a convergence of CO2 assimilation rate and other physiological, morphological, and biochemical characteristics between the upper and lower canopy occurred. However, differences in altitudinal response among individual traits and species were found. Such plasticity in acclimation of leaves and needles has the potential to cause substantial change in the photosynthesis of individual parts of forest canopies within the vertical profile and their contribution to the overall carbon balance of vegetation.
The relationships of soil CO2 flux with selected Norway spruce root parameters and sterol content in the soil
Holub, Filip ; Fabiánek, Tomáš ; Večeřová, Kristýna ; Moos, Martin ; Oravec, Michal ; Tříska, Jan ; Marková, I. ; Edwards, Magda ; Cudlín, Pavel
The flow of CO2 from the soil is a very important part of the carbon cycle in an ecosystem. The aim of our work was to determine how roots and rhizospheric fungi contribute to CO2 flux from the soil. Preliminary results from two years of research are presented. The research on how root biomass as well as ergosterol and phytosterol contents in roots and soil affected CO2 flux from the soil was conducted in a 108-year-old Norway spruce (Picea abies (L.) Karst.) forest in the Drahany Highlands during 2010 and 2011. CO2 flow was measured using a LI-8100 portable closed gasometric system (Li-Cor, USA). The dry weight and volume of individual root categories (< 1 mm, 1–2 mm, 2–5 mm, > 5 mm), C and N contents in the roots, as well as ergosterol, β-sitosterol, and campesterol contents in the soil and roots were determined from root-containing soil samples located in the circular measurement chamber. In addition, sterol content was determined in the soil only. Our soil respiration results correspond with the findings of Buchman (2000) who found respiration values between 5–7 μmol CO2 m−2 s−1 in a 111-year-old spruce forest. A significant influence on soil respiration was proven only for sitosterol content in the soil. The relationships among soil CO2 flux, root characteristics, and nitrogen and sterol contents in the roots and soil are discussed.
Comparison of techniques for determination of monoterpenes in forested area
Křůmal, Kamil ; Večeřová, Kristýna ; Holišová, Petra ; Urban, Otmar ; Pallozzi, E. ; Guidolotti, G. ; Calfapietra, C. ; Večeřa, Zbyněk
In this work three different techniques (1 online and 2 offline) for determination of monoterpenes in forest were compared. Monoterpenes were determined by PTR-MS (Proton Transfer Reaction Mass Spectrometer), cylindrical wet effluent diffusion denuders and tenax tubes.

National Repository of Grey Literature : 11 records found   1 - 10next  jump to record:
See also: similar author names
1 Večeřová, Karolína
1 Večeřová, Klára
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