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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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Intraspecific variability in seeds nutrient stoichiometry
Kesl, Tomáš ; Mašková, Tereza (advisor) ; Konečná, Marie (referee)
Immediately after germination, the plants depend on the nutrients stored in the seed from which they germinated, until the nutrient intake is completely replaced by the mature leaves and roots. Nutrients in seeds are important for early development of vegetative organs. Their content and concentration in seeds can be influenced by various factors such as nutrient availability in soil, latitude, temperature, photoperiod, granivory and competition. This bachelor's thesis summarizes current knowledge about intraspecific and interspecific variability of seed nutrient stoichiometry, specifically nitrogen, phosphorus and carbon, as they most often limit plant growth. For all three elements, common and different trends can be observed, both at the intra-species and inter-species level. The only trend comparable between the intra-species and inter-species level is correlation of carbon seed concentration and latitude, while at the inter-species level there is also the opposite trend of negative correlation of latitude and carbon concentration in seeds. Other observed trends are not comparable between the intra-species and inter-species level. It is not possible to compare these trends, as there is lack of studies on the variability of seed nutrient stoichiometry. Therefore it is necessary to focus on seed...
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Narrowly
Sádecká, Lucia ; Králíková, Lucie (referee) ; Mazanec, Martin (advisor)
Len len is about the process. Originating in environmental issues and reflecting the processuality of the creation of a work of art. Processes from production to product, from tradition to the present, from memory to experience, from fast to slow, from imperfection to perfection, from the impersonal to the personal, from beginning to end. I deal with work with textiles as a classic medium, while I devote myself to the cultivation of flax as the original, in our country, raw material for the production of textiles. From the beginning, I watch carefully as it grows, I take care of it and I patiently expect the time of collection and subsequent processing. This phase is very important for me, as it brings with it various procedures, applied in old proven technologies, in interaction with people from whom I learn the craft and who shape the whole process, but especially from behind, observe how I am doing, what I managed. It is a personal and at the same time technical record of a two-year effort.
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Possibilities of using of Vitis vinifera as a source of raw materials for cosmetic production
Hanáková, Pavlína ; Vítová, Eva (referee) ; Zemanová, Jana (advisor)
This bachelor thesis deals with preparation of extraction from various parts of grapevine and their consequent use in the manufacture of cosmetics. The theoretical part is focused on general characteristics of grapevine, its taxonomic classification, occurrence and cultivation. Subsequently, the chemical composition of grapevine parts and their uses in cosmetic, food and pharmaceutical industries is described. The final part is devoted to particular types of extractions and methods of determinativ of total phenolic substances. The experimental part deals with the optimization of the prepared extract in order to obtain the extract with the highest amount of total phenolic substances with respect to production costs. Factors such as selection of the appropriate solvent and extraction time are examined. 50% ethanol at the room temperature was found to be an optimal solvent. Finally, the physical and chemical properties, such as density, pH and refractive index were determined for the purpose of producing a material safety data sheet. The extract was processed into cosmetic products.
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Physical dormancy of seeds
Jiroušková, Anna ; Ponert, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Physical dormancy of seeds is a widespread adaptation, allowing plant seeds to time the germination to a suitable season. Seeds with physical dormancy possess hard seed coats, which are impermeable to water and sometimes also to gases. This allows seeds to create a long-term seed bank and to wait for favourable conditions even for years. There are two main mechanisms, which break physical dormancy and enable water to enter the seed. The seed coat can be disrupted through the whole surface, or in one specialized place only. The disruption through the whole surface is common in the seeds dispersed by endozoochory. In this case, the long-distance seed dispersal brings an important advantage. In physically dormant seeds, which are dispersed by other ways, a complicated structure called water gap is usually present in the seed coat. Water gap responds to exogenous signals and controls when the water enters the seed. In such a case, physical dormancy can be broken as a response to annual or diurnal temperature fluctuations, which times germination into a proper time of the year. Another species germinate in response to high temperatures during a fire. This ensures, that seedlings emerge in suitable conditions with a high level of available nutrients, low competition and that they can restore the damaged...
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Germination of long-term storaged seeds of selected grass and legumes
VONDRÁŠEK, Vít
Quality reproductive material is created in the fields but its subsequent quality and the general ability to germinate may be affected by many other factors. The fundamental and necessary capability of the seeds is their germinability. In my thesis I selected seeds approximately 6 - 8 years old of certain types of grass or clover plants (Trifolium repens, Trifolium pratense, Medicago sativa - Zuzana, Medicago sativa - Pálava, Medicago lupulina, Trifolium hybridum - Oderský, Anthyllis vulneraria and Onobrychis viciifolia) and I monitored their germinability, its dynamics and capacity. Subsequently, I also used fresh seeds to compare the results and to demonstrate how seeds of different ages may differ. The experiment was performed under home conditions. All seeds to be germinated were placed on Petri dishes on which I maintained stable humidity. I monitored germinability of the seeds in previously set intervals after 2, 3, 5, 7, 10 and 15 days. Originally, the plan was to measure germinability also after 21 days but the germinating material did not last that long and losses were detected as early as after 15 days. I saw big differences between the individual species. Some of them germinated very well and their dynamics was high (Trifolium repens, Medicago sativa - Zuzana, Medicago sativa - Pálava), while others did not germinate at all or very little (Onobrychis viciifolia, Anthyllis vulneraria). In some species I even observed differences in germination dynamics.
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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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Hodnocení strojů pro pásové zpracování půdy
HEŘMÁNEK, Aleš
The Bachelor thesis deals with strip tillage technology. It describes possibilities of its use and technological options, which are available at present. Furthermore, not only advatages of the strip tillage technology towards the environment and soil are described in this theses, but also certain limitations and pitfalls, which may appear while using such technology. The first part of the thesis is focused on history of soil proccessing starting with the very first agricultural tools. Use of the first mechanization operations with soil while using the first plows, are captured in this thesis, followed by a description and distribution of minimization technologies, including strip tillage technology. The information are complemented by a description of agriculture machinery. The practical part deals with metodology and results of measuring related to performance of a selected seeder, the Mzuri PRO-TIL 4T. One of the evaluating criteria was setting up the depth of soil processing, the number of lumps as well as the amount of plant remains in the particular strips of the area, the number of grown plants, placing seeds into the desired depth and efficiency of the specific set. The thesis is complemented by specifications of the agriculture company HZT Technik-servis, a.s., as well as by a simple analysis of investment and operating costs.
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Changes in timing of germination caused by neighbouring seeds and how it is connected with species traits.
Kos, Pavel ; Weiser, Martin (advisor) ; Hadincová, Věroslava (referee)
The time when the seed germinates is very important. Ability to change the time of germination may be very advantageous. It allows the emerging seed to choose the best time according to abiotic conditions, and also to avoid of competition with neighbouring individuals. The seed reacts not only on adult plants and seedlings, but also on other seeds, with which is able to communicate. For a better understanding to this mechanism I conducted an experimental study with twenty-six species. The species were selected according to their position in long succession seres of mesic/xeric abandoned fields in Český kras. The seeds were left to germinate in pairs in all combinations among them. Here I present the results where I show how the time of emergence changes, depending on presence of neighbouring seed. Also, I show how these changes in germination are related to species specific traits. Out of this, I tried to influence communication between seeds by adding activated carbon. Activated carbon should stop the communication by highly absorbing surface. The time of germination of seeds which germinated alone was not proportional to the time of germination of seeds which germinated with neighbours. This correlation showed up like nonlinear, late-emerging seeds emerging unproportionally later when emerging...
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