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Differences in photosynthesis and plant water status between coppice and high forest
Matoušková, Marie
This diploma thesis focuses on comparison of photosynthesis and tree water status between high forest and coppice of Quercus petraea (Matt.) Liebl. Four different types of management were investigated during vegetation season 2016: high forest, coppice on clear-felled site, coppice with standards and seedlings. Methods of leaf gas exchange and water potential measurements allowed to study transpiration, photosynthesis and its response to light and CO2 concentration and leaf water potential. All these physiological parameters were studied as linked to weather conditions and various levels of drought stress. When the soil water was not limiting factor trees in all variants of experiment behaved similarly. However, during mild to severe drought stress the coppice was superior to seedlings and to high forest. It showed higher photosynthesis rate (2.49 umol m-2 s-1) than seedlings (0.86 umol m-2 s-1), both under moderate water stress. Coppice also had higher stomatal conductance and quantum yield of fluorescence than high forest which allowed to higher photosynthetic rates. The lowest value of predawn water potential was in high forest (-3.27 MPa) whereas highest in coppice (-2.01 MPa) which indicated better water availability and lower evapotranspiration demands imposed on coppice sprouts due to their lower height and therefore lower overall aerodynamic conductance. Response of net photosynthesis to CO2 concentration revealed higher carboxylation rates in high forest than in coppice but low stomatal conductance was a reason for overall lower photosynthetic rates in high forest than in coppice. Due to its superiority under water stress coppice forest may be a viable option for forest management on dry sites during the climate change.
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Regulace plevelů v porostu mrkve obecné pěstované na semeno
Coufal, Václav
The aim of this bachelor thesis was the elaboration of a literature review on weed control in carrot (Daucus carota) for seed production and to conduct laboratory experiment focused on testing selectivity and efficacy of herbicides in carrot using the chlorophyll fluorescence imaging technique. The aim of this experiment was to evaluate the efficacy of selected herbicides on common lambsquarters (Chenopodium album) and their phytotoxicity on carrot plants under pre-emergence and post-emergence applications. In addition, preemergence applications were performed in two variants simulating contrast soil conditions. The first was an organic substrate and the other quartz sand. Altogether, 8 herbicide active ingredients were used, some of which are registered in carrots, and some were previously tested abroad, thus providing the potential for improving the system of chemical weed control in carrots. These were carfentrazone-ethyl, clomazone, diflufenican, linuron, mesotrione, metribuzin, pendimethalin and S-metolachlor. Under preemergence application in the organic substrate, the best results were achieved with linuron and pendimethalin, both exhibiting high efficacy against common lambsquarters and low phytotoxicity to carrot plants. Preemergence application of herbicides in quartz sand showed a clear increase of phytotoxicity of preemergence herbicides. Increased phytotoxicity was evident in almost all herbicides, but mostlyin linuron. On the other hand, a decrease in phytotoxicity was found in diflufenican. The lowest phytotoxicity rate was observed for pendimethalin. In early post-emergence applications, the efficacy of all selected herbicides ranged above 90%. The lowest level of phytotoxicity was observed for pendimethalin, linuron, clomazone and mesotrione. Chlorophyll fluorescence imaging represents a very good tool for early assessment of the physiological herbicide effect, however, the evaluation by chlorophyll fluorescence in herbicides affecting directly photosynthesis led to overestimation the effects in comparison with other herbicides.
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Vývoj metodologické a technologické platformy pro neinvazivní odhad fenolických látek v listech a bobulích
ŠEBELA, David
Plant optical signals can serve as important source of information about biochemical and physiological processes in plants. These signals are influenced by compounds synthesized by plants during primary or secondary metabolism and thus, can also serve as their qualitative and quantitative indicators. Light reaching plant surface (leaf or fruit) can undergo three main pathways- it can be (i) reflected, (ii) absorbed or it can (iii) transmit through plant material. The probability of these three processes depends on particular wavelength of incident irradiation and on the morphological characteristics of plant tissues themselves. As such, plant contains various spectrum of photosynthetic pigments and fluorescent compounds which can either reflect, absorb or pass incident irradiation through at specific wavelengths. Biophysical techniques working with these optical properties of plant pigments and/or other compounds have become universal and common tool in basic and applied research. To quote some example, chlorophyll fluorescence imaging, UV induced fluorescence or spectroscopic techniques are on the top of interest thanks to its non-invasive nature, allowing maintain the integrity of measured cells or the whole plant constituents. The main aim of this thesis is to provide a comprehensive study on the possibility of non-invasive monitoring of phenolic compounds in the leaves and fruits.
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Imaging of fluorescence emission signals from healthy and infected leaf tissues
BENEDIKTYOVÁ, Zuzana
Auto-fluorescence emission of plant tissues can be a powerful reporter on plant biochemistry and physiology since it originates in substances inherent to primary or secondary metabolism. Plant bodies contain a plethora of intrinsic fluorescent compounds emitting practically all wavelengths of visible light. Moreover, the spectrum of fluorescent reporter signals was recently extended by a variety of fluorescent proteins that provide a new tool to mark whole cells or sub-cellular structures, study protein localization and monitor gene expression and molecule interactions. The imaging of such fluorescence signals reveals a possibility to acquire the information from as many as millions of points simultaneously, in vivo and in a non-invasive way thereby preserving integrity of cells and whole organisms. Imaging is particularly suited to visualize heterogeneity such as a localized immune response to invading pathogens. It can be applied both at macro- as well as micro-scales in two and three dimensions. The recent advancement in microscopy, the multi-photon microscopy, has made possible to monitor fluorescence signals, such as NAD(P)H fluorescence from intact leaf interior, that have been hidden to single-photon techniques.
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