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Klíčivost semen, metody stanovení a její ovlivnění faktory prostředí
KRAUS, Jindřich
We compared germination rate and germination dynamics of species under different seed stratification treatments (dry, wet, temperature variation). The experiment was performed in laboratory conditions using seeds of ten species from commercial sales. The home site advantage was tested in a field experiment assessing seed germination of three species from four localities differing in moisture and seeds from commercial sales. We analysed the data using generalized linear models.
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Studying the regulation of expression of genes involved in barley malting quality
Hoffmannová, Viktorie ; Svobodová, Leona (advisor) ; Lipavská, Helena (referee)
Barley (Hordeum vulgare L.) is a grain cultivated as an agricultural crop across many varying climatic areas of the world. It is mainly used for its feed and brewing industry properties. This work will focus on studying the malting process on a molecular level, which mainly includes the genes for degradative enzymes of storage proteins, starch and compounds of endosperm cell walls. We shall observe how all these components interact during malting and other processes of brewing beer. It is known that malting quality parameters are tied to several genes, whose expression is regulated. These regulatory pathways will also be included in this work.
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Ecophysiological relevance of extreme sensitivity of orchids to nitrates
Figura, Tomáš ; Ponert, Jan (advisor) ; Tylová, Edita (referee)
Many orchid species are seriously endangered at present. Reasons for their disappearing from natural habitats remain often unclear. Orchids depend on mycorrhizal symbiosis in nature, however only little is known about this symbiosis. Seeds of some species do not germinate in vitro, making their cultivation for scientific and rescue purposes impossible. We found that seed germination of one of such reluctant species, Pseudorchis albida, is strongly inhibited by nitrates even at extremely low concentrations. As this species prefers oligotrophic mountain meadows, nitrate-induced inhibition probably take place in natural conditions. Surprisingly, we found similar but slightly weaker inhibitory effect also in typical mesophillic species and even in slightly eutrophic ones. The sensitivity to nitrates correlates with trophy level of species canopy. This inhibitory effect of nitrates could be weakened by application of a range of growth regulators, including auxins, cytokinins and gibberellins, and also by mycorrhizal fungi. The action of nitratereductase is essential for this inhibitory effect of nitrates. Experiments with NO donors, scavengers, and NO quantification are pointing right at NO as compound which perhaps mediates nitrate inhibitory effect. Based on these results, the nitrate inhibitory...
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Mechanisms that control physiological seed dormancy
Řezková, Natálie ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physiological dormancy is an important developmental trait ensuring that seed does not germinate when the environmental factors are appropriate only temporary. The transition from seed dormancy to germination is regulated by a large number of factors and the phytohormone abscisic acid (ABA) plays a crucial role. Enhanced response to ABA and its biosynthesis is a key mechanism in dormancy induction and maintenance. ABA interacts antagonistically with gibberellins (GAs). Therefore GA biosynthesis and ABA catabolism are positive germination regulators. However, other phytohormones are also involved in the regulation of dormancy and germination. The most studied is ethylene which supports germination similarly to GA. Numerous factors affect dormancy at molecular level, namely chromatin remodeling, gene products that function only in dormancy regulation [e.g. DELAY OF GERMINATION 1 (DOG1)] or gene products that mediate seed response to environmental factors. The dormancy, its induction, depth and release, is driven not only by environmental conditions affecting mature seeds, but also by conditions acting during seed maturation in a maternal plant when the primary dormancy is induced. Requirements for dormancy release and germination induction may vary considerably between species. The physiological...
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Chrysophyte stomatocysts - encystation and excystation dynamics - bentic resting stages of chrysophytes
Mušálková, Petra ; Němcová, Yvonne (advisor) ; Juráň, Josef (referee)
The resting resistant stage has several important roles for phytoplankton microorganisms. It protects them from hostile conditions, allows them to spread to new locations and is often part of their life cycle. Chrysophytes form large populations for only a short part of the year, and therefore the formation of a resting stage is key for them to re-establish a vegetative population the following year. Chrysophyte resting stages are called stomatocysts, which are silicified and have a unique species-specific morphology. They can be form after both sexual and asexual reproduction. This is an understudied area. Most described stomatocysts are not assigned to species and much is not known about the triggers of encystation and excystation. It is thought that a combination of external (temperature, light, nutrients) and internal (cell age and cell concentration) factors are involved. So far, only sexual encystation in Dinobryon cyindricum and Synura petersenii has been studied in detail. My diploma thesis is based on laboratory experiments with Ochromonas tuberculata, Synura uvella and two strains of Synura petersenii. The aim of the study was to investigating whether external conditions such as temperature and lack of nitrogen or phosphorus have the effect on asexual encystation and whether it is...
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Mechanisms that control physiological seed dormancy
Řezková, Natálie ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physiological dormancy is an important developmental trait ensuring that seed does not germinate when the environmental factors are appropriate only temporary. The transition from seed dormancy to germination is regulated by a large number of factors and the phytohormone abscisic acid (ABA) plays a crucial role. Enhanced response to ABA and its biosynthesis is a key mechanism in dormancy induction and maintenance. ABA interacts antagonistically with gibberellins (GAs). Therefore GA biosynthesis and ABA catabolism are positive germination regulators. However, other phytohormones are also involved in the regulation of dormancy and germination. The most studied is ethylene which supports germination similarly to GA. Numerous factors affect dormancy at molecular level, namely chromatin remodeling, gene products that function only in dormancy regulation [e.g. DELAY OF GERMINATION 1 (DOG1)] or gene products that mediate seed response to environmental factors. The dormancy, its induction, depth and release, is driven not only by environmental conditions affecting mature seeds, but also by conditions acting during seed maturation in a maternal plant when the primary dormancy is induced. Requirements for dormancy release and germination induction may vary considerably between species. The physiological...
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Vitality and germination juniper (\kur{Juniperus communis}) seeds
OKROUHLÁ, Ilona
The thesis focuses on the fertility and vitality of common juniper seeds (Juniperus communis). Random galbula samples from two areas were tested. Amount of seeds per one galbula were compared, seed fullness and vitality were compared via the colouring method, as well as the weight, as well as a try to cancel the dormancy using gibberelinic acid GA,, following the aim to plant more seedlings. The results were compared to seed values and to findings from other authors. If the issue of lower seed fullness and vitality is clarified, more suitable methods of juniper population proliferation and support maybe worked out.
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Seed germination and seedling recruitment of Iris sibirica depending on the type of management
HOŘEJŠÍ, Edita
This work continue on a bachelor's work which investigated production characteristics of the plant species Siberian Iris (Iris sibirica). The aims of the presented work are reproductive properties by seeds of Siberian Iris in relation to the seed germination and with various meadow managements. Seeds of Siberian Iris (collected in 2015 and 2016) were investigated in laboratory condition and at meadow near the pond Dolní Stržený (Dlouhá Lhota, of the Tábor District). Seeds were divided into groups according to 4 treatments: without intervention, scarification, thermal stratification and cold stratification. The field experiment runs from September 2016 to August 2017.The aim was to find out the most appropriate type of management (mowing, disturbance) that would promote seed germination and seedling recruitment. Results from the both experiments: a positive effect of germination after the scarification, better recruitment of seeds in square without intervention, seeds probably needs to be stored for a longer period before sowing. These results cannot be generalized, because small number of repetitions were performed. All the obtained data was discussed and recommendations for the plant management were formulated.
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Ecophysiological relevance of extreme sensitivity of orchids to nitrates
Figura, Tomáš ; Ponert, Jan (advisor) ; Tylová, Edita (referee)
Many orchid species are seriously endangered at present. Reasons for their disappearing from natural habitats remain often unclear. Orchids depend on mycorrhizal symbiosis in nature, however only little is known about this symbiosis. Seeds of some species do not germinate in vitro, making their cultivation for scientific and rescue purposes impossible. We found that seed germination of one of such reluctant species, Pseudorchis albida, is strongly inhibited by nitrates even at extremely low concentrations. As this species prefers oligotrophic mountain meadows, nitrate-induced inhibition probably take place in natural conditions. Surprisingly, we found similar but slightly weaker inhibitory effect also in typical mesophillic species and even in slightly eutrophic ones. The sensitivity to nitrates correlates with trophy level of species canopy. This inhibitory effect of nitrates could be weakened by application of a range of growth regulators, including auxins, cytokinins and gibberellins, and also by mycorrhizal fungi. The action of nitratereductase is essential for this inhibitory effect of nitrates. Experiments with NO donors, scavengers, and NO quantification are pointing right at NO as compound which perhaps mediates nitrate inhibitory effect. Based on these results, the nitrate inhibitory...
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Seed dormancy mechanisms of mycoheterotrophic plants
Figura, Tomáš ; Ponert, Jan (advisor) ; Weiser, Martin (referee)
Seeds of mycoheterotrophic plants known as dust seeds which are typical for the family Orchidaceae and 11 other families have inner (physiological, morphological) and outer (physical) dormancy. Dormancy breaking it is a necessary step for a seed to germinate. For breaking the exogenous dormancy it is necessary to break both inner and outer testa, which can be done by scarification. Chemical scarification, mostly done by chlorine, is commonly used and it seems to be the best way for breaking dormancy and also for sterilization of seeds. Other sterilization agents as ethanol and sulfuric acid are also commonly used. For breaking the inner (physical) dormancy, application of growth regulators can be useful, especially in the case of cytokinins, specifically kinetine. Abscisic acid induces dormancy and ethylene induces germination. Anorganic forms of nitrogen have also inhibitory effects for germination at least for some species. Seeds of most orchid species also need a period of chilling after sowing and for germination they mostly need temperature around 23řC.
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