|
|
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.
|
|
|
Supercritical Fractionation of Volatiles and Non-volatiles from Different Plant Sources
Topiař, Martin
The focus of this work was on using the SFE combined with different fractionation techniques (additional separator, sorption on silica gel in one step with the extraction) in a range of pressures and temperatures (9–30 MPa, 40–50 °C) to enhance volatiles in extracts from the leaves of eucalyptus. Its essential oil is widely used in cough pills or toothpastes and in addition, several studies proved insecticidal and repellent activity of eucalyptus extract.1,2 The efficiency of SFE in terms of extract composition and yield was compared with hydrodistillation. The composition of volatiles in the isolates was determined using GC-MS and GC-FID.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22015061709330 - PDF
|
|
| |
|
| |
|
| |
|
|
Suggestions of science field trips to selected locations around Horažďovicce with using in teaching natural history at the 2nd primary school
ZÁBRANSKÁ, Věra
The main aim of this thesis is the suggestion of excursions into certain places in the region of Horažďovice for pupils from 6th to 9th grade at elementary school. The thesis is divided into the theoretical part and the part focused on preparation of these excursions. The theoretical part is concerned with plan and tuitional methods which are useful for preparation änd realization of the excursions. The second part is dedicated to the description of natural environment of the region of Horažďovice and particular localities. They consist of protected areas and nature reserves - Prácheň, Pučanka and Svaté Pole. Excursions are focused on processing of knowledge gained during natural science lessons and these localities were chosen thanks their various kinds of animals and plants.
|
|
|
Ecology and conservation of invertebrates at anthropogenic sites
TROPEK, Robert
This thesis deals with communities of arthropods (and partly also vascular plants) colonising diverse anthropogenic sites. It reveals a conservation potential of these sites and focus on ecological requirements of both whole communities and individual species generalising these findings for usage in restoration of these sites.
|
|
|
Differences in CO2 Extraction of Vegetable Oils, Essential Oils, and Minor Components from Plants
Sovová, Helena
Significant progress in understanding the phenomena that control supercritical fluid extraction from plants was made in the last years and is reflected in the literature. Combination of chemical engineering approach and botanical knowledge has appeared to be fruitful for the choice of extraction model and even for the prediction of extraction kinetics. This contribution refers to the papers utilizing knowledge of plant microstructure and location of extracted substances together with extraction equilibrium and attempts to specify the differences among extraction kinetics of vegetable oils, essential oils, and other substances. The most abundant substances like vegetable oils in seeds can be regarded in first approximation as non-interacting with plant matrix, in contrast to the minor components whose equilibrium concentration in CO2 is affected by their adsorption on matrix and often also by co-extracted substances.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22012102414100 - PDF
|
|
| |
|
|
Function of honey-bee (Apis mellifera) in see industry of field crops.
PŠENIČKOVÁ, Zuzana
In this dissertation I am trying to point out the importance of the honeybee in the pollination of plants and the connection between the plant and the honeybee. The honeybee is essential and indispensable part of agricultural production that increase in the hectare production. It is also importat in forests, fields and in orchards. In the introduction there is a telling about bee colony and alternative ways of pollinate. In this dissertation I outline economic and ecological features of beekeeping and problems that beekeepers have to solve, some grants from the European Union that help to our beekeepers. In conclusion there are described some problems and different opinions for geneticaly modified plants and their influence for the honeybee.
|
guest ::
