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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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Seed germination of selected crops after low-temperature treatment
PETRÁŠKOVÁ, Kamila
The influence of low-temperature plasma on the different seeds is currently one of the most used techniques in agriculture. The aim of my bachelor thesis is to monitor and evaluate the effect of low-temperature plasma on the seeds of maize sow (Zea mays L.) and oilseed rape (Brassica napus L. napus), particularly on the germination of the seeds, germination rate and germination energy. These characteristics were measured by germination tests and they are expressed as a percentage. The submitted thesis informs whether the stimulation of the seeds by plasma affects these plants and if so, whether the influence is positive or negative.
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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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Inquiry methods in educational area Man and his world: Seeds, fruit and young plants
Nikrýnová, Alena ; Stará, Jana (advisor) ; Straková, Jana (referee)
This diploma work deals with the issues of inquiry methods of teaching at primary schools. The theoretical part provides some reflections on contributions and limits of inquiry methods and defines basic inquiry skills. Activities concerning the theme "seeds, fruit, young plants" for the pupils of the 1.-4.grade are suggested in the practical part. Nine of them were tried out in classes. The results of the action research are summarized in the conclusion. They are related to these research questions: 1. How to adjust inquiry activities in a suitable way for their use in the given classes at primary schools? 2. How do children react to this work style? 3. What demands does this work style make on teachers? 4. What problems concerning partial inquiry skills could emerge? How to continue working at them?
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Cemical composition of hemp (\kur{Cannabis sativa}) and possibilities of its utilization as animal feed
NĚMCOVÁ, Michaela
Cannabis sativa L. is an annual cultural plant used from ancient times up to the present in many spheres of the human life. The aim of this bachelor study was to summarize on the basis of literature sources the information about chemical composition of the hemp seed (basic composition, content of amino acids, fiber, vitamins and specific substances, etc.), genetic variability in the substances content, and possibilities of utilization of the hemp seed and also plant residues as feed. Feeding hemp seeds to poultry increases egg production and enriches egg yolk with carotenoids, - 3 and - 6 fatty acids and decreases the cholesterol content. In case of broilers, hemp seeds increases the weight of the breasts, thighs, liver, stomach, intestines and the portion of abdominal fat. Hemp seed cakes have a positive effect on rumen function, support reception of neutral detergent fiber and increases the unsaturated fatty acids content in the meat. Hemp oil relieves stress and improves immunity of the fed animals.
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