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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Očekávané dopady změny klimatu v ČR a jejich vztah k rozšíření, růstu a vývoji teplomilných druhů ovocných dřevin / Expected impact of climate change and their relationship to distribution, growth and development of thermophilic fruit trees in the Czech Republic

Ciprová, Lenka January 2016 (has links)
The main objective of the Master's thesis is to collect and evaluate scientific information and processing datasets of expected impact of climate change and their relationship to distribution, growth and development of thermophilic fruit trees in the Czech Republic. The first and second parts of the literature research are focused on the impact of global warning and economic/agricultural conditions on growth and development of the thermophilic species of fruit trees at the global, regional and local levels. The next section deals with the relationship of thermophilic fruit trees production with climatic, soil conditions, phenology and economic factors, which greatly affect yields in the Czech Republic. This study was conducted on daily meteorological variables (sum of global radiation, maximum and minimum temperatures) and annual yield datasets of Apricot (Armeniaca vulgaris) and Peach (Prunus Persica) trees at the country level for the period 2005-2015. The obtained new results can be divided into 3 parts: (1) catalogue of meteorological phenomena during the growing season, (2) catalogue of meteorological phenomena during the period of dormancy, and (3) statistical analyses of meteorological extreme events during flower/flowering formation of the Apricot and Peach trees. Results based on the analysis of historical phenological observations and descriptive statistics of yield parameters of thermophilic fruit trees over the study period shown that (i) mainly spring phenological stages of the thermophilic fruit trees shown a tendency to an earlier onset, (ii) the highest variability in the phenophase onsets of Apricot and Peach are in the inflorescence emergence and beginning of flowering, (iii) the coefficients of variation were higher for Peach with year-to-year variations in crop yields, and (iv) Peach had the largest fluctuations in average annual production (from 0.48 to of 0.72 tha-1 year-1).
12

Moderní postupy hodnocení kvalitativních parametrů potravin / Modern Approaches in Qualitative Aspects of Foods Assessment

Tobolková, Blanka January 2014 (has links)
Antioxidant properties and some other characteristics of selected organic and conventional products (wine, spelt flours) were evaluated in view of their potential utilization as markers suitable for food unambiguous differentiation according to the affiliation to production system. Beside these, study of fruit juices stability during storage in dependence on different technological procedures of juice processing was performed. In both cases, combination of dominantly EPR and UV/VIS spectroscopy but also other methods (e.g., HPLC, AAS, electrophoresis) was applied to evaluate the stability and antioxidant properties of selected samples. Statistical methods, especially methods of multivariate statistics were used to assess the influence of production and technological-processing operations on antioxidant status of foods and their selected characteristics. Qualitative analysis of Slovak and foreign organic and conventional wines proved that their antioxidant properties are influenced by production system, vintage and variety. On the basis of statistical analysis, descriptors of AAE, kTEMPOL and %RS were selected as the most powerful markers for Slovak organic and conventional wines discrimination. The discrimination of white and red organic and conventional wines possessed 100% and 95.2% correctness, respectively. High correctness of differentiation of Slovak and foreign wines was also achieved. Monitored descriptors of antioxidant activity of spelt flours varied in dependence on season, origin, variety, production system and depend also on way of spelt treatment, although this effect is not so significant. It was also confirmed that the type of extraction agent substantially affects the composition of extracts including polyphenols and flavonoids concentration, affecting thus also their antioxidant activity. Mixture of 50% ethanol/water was selected as the most promising extraction system. Although the results of individual spectroscopic assays revealed high variability and often ambiguous trends, the differences found were sufficient for successful differentiation of both wines and spelt flour samples according to the selected criteria by multivariate statistical processing of the data. Influence of changes in technological procedures of fruit juice processing (nitrogen atmosphere application, utilization of caps with oxygen scavengers) on radical-scavenging properties of 100% pineapples juices with pieces of pineapple and 100% orange juices with pulp was assessed as well. Results obtained proved that antioxidant activity of juices varied in dependence on storage conditions (temperature, storage time, light exposure) and depends also on origin, variety and quality of fruit used. However, the application of nitrogen atmosphere and active packaging materials is not sufficient enough to eliminate the oxidation reactions in juices, but changes in antioxidant activity are better predictable. It can be concluded that EPR spectroscopy could be effectively applied for wines and spelt flours differentiation according to the way of production and to assess the stability of food products, either alone or in combination of UV/VIS spectroscopy and the other methods, utilizing multivariate statistics for processing of experimental data.
13

Analýza sexuálního feromonu ovocných mušek rodu Ceratitis fasciventris, Ceratitis anonae a Ceratitis rosa / Analýza sexuálního feromonu ovocných mušek rodu Ceratitis fasciventris, Ceratitis anonae a Ceratitis rosa

Faťarová, Mária January 2013 (has links)
Ceratitis fasciventris, Ceratitis anonae and Ceratitis rosa are polyphagous agricultural pests originating from African continent. Their behaviour is heavily altered by pheromones. Insect chemical communication channels are species-specific, represents taxonomic and reproduction barriers. Taxonomy of this group (so-called Ceratitis FAR complex) is unclear. Therefore new chemical approaches along with genetic tests for identification of entities within the cryptic species FAR complex are being developed. To study multi-component mixtures of male volatiles originating from the three mentioned fruit fly species, comprehensive two-dimensional gas chromatography with time- of-flight mass spectrometer (GC×GC-TOFMS) was used. A number of compounds were identified, out of which 23 were found to be distributed and shared among the studied species, 11 out of these were present in all three species. Analyses of male pheromone volatiles, using gas chromatography combined with electroantennographic detector (GC-EAD) revealed 4 common compounds with antennal activity shared among three studied species: methyl (E)-hex-3-enoate, 6-methylhept-5-en-2- one, linalool, and methyl (2E,6E)-farnesoate. The species-specific EAD active compounds in C. fasciventris were esters of isomers of hexenoic acid, whereas isomers of...

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