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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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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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Role proteinů tepelného šoku v regulaci klíčení semen
Hýsková, Anna
Seed germination is one of the most important phases of the plants' life cycle. This process is regulated by many external and internal factors, which interactions impact the course of germination, seed vigor and overall prosperity of the plant. Heat shock proteins (HSPs) are a part of protective mechanisms, but their role in seed germination is not quite understood. This thesis entitled “The role of heat shock proteins in the regulation of seed germination“ reviews processes of seed germination and outlines the role of HSPs in plants. The experimental part compares the previously documented HSP expression profiles with protein abundances, analyzes the effect of HSP mutation on seed germination and response to stimuli, including phytohormones, salt and heavy metals. These experiments revealed a putative role of HSP70-2 and HSP70-5 in seed germination and highlighted the role of the UBC system in the regulation of HSPs.
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Historický vývoj a možnosti pěstování fíkovníku smokvoně (Ficus carica L.) v podmínkách ČR.
Malárová, Michaela
This bachelor thesis is focused on the history of growing common fig Ficus carica L. in our country, characterizes fig tree greenhouses with the best known examples, deals with the issue of fig tree adaptability in relation to growth physiology, the course of dormancy and frost resistence. The thesis defines the sum of chilling hours and compares them with other fruit species. After evaluating the available information, it can be stated that due to its ability to adapt to climatic conditions, the fig tree can be grown in outdoor cultures all year round in the warmest regions of the Czech Republic.
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Hodnocení vybraných znaků perspektivních odrůd broskvoní
Horsáková, Jana
Dissertation work deals with the evaluation of the selected characters of promising peach varieties grown in the genepool collection and pilot testing block. The evaluation took place between year 2011 to 2013. The work can be divided into three thematical units. The first part deals with the health condition, specifically monitoring of the occurrence of European stone fruit yellows phytoplasma (ESFY) and the plum pox virus (PPV). The second part focuses on the physiological events occurring in flower buds (dormancy, microsporogenesis, frost resistance) and the third unit deals with pomological characteristics of varieties and the economic evaluation of varieties which are already introduced in the commercial cultivation. In the literature section the origin and the spread, world production of peaches and the current situation in the Czech Republic are descibed and a chapter about peach breeding is included as well. Further, chapters characterizing dormancy, microsporogenesis and frost hardiness are described in the work. Literature section also includes content substances and health-promoting substances in peach fruit. The last chapter describes the diseases causing economically significant losses in peaches. In the experimental part the incidence and symptoms of phytoplasma ESFY and synergism between PPV and ESFY was evaluated. The effect of the PPV infection on content of the total polyphenols and the antioxidant activity of fruits was investigated. Further, the termination of dormancy, microsporogenesis and frost resistance of flower buds was evaluated. Significant part of work was the pomological evaluation of selected varieties from genepool collection and evaluation of varieties in pilot testing block conditions. The results show that in peach orchards trees infected by phytoplasma ESFY show various symptoms of the disease which depend on host genotype. Synergism between Plum pox virus (PPV) and European stone fruit yellows phytoplasma (ESFY) has not been confirmed. PPV infection results in increased amount of the antioxidant activity and total polyphenols in peach fruits.Varieties can be divided into 3 groups by the term of termination of endogenous dormancy, paticulary, varieties with early termination, varieties with medium termination and varieties with late termination of dormancy. Evaluated varieties differ, either, in duration and date of occurence of phases of microsporogenesis. The process of dormancy and microsporogenesis of individual varieties is different and is influenced by the weather conditions of the year. There are differences in frost resistance between peach varieties. The highest degree of frost hardiness was set by the 'Lesiberian'. Studied peach varieties show differences in pomological, biological and economic characters. From the evaluated group of varieties the promising are 'Venus', 'Fantasia', 'Fidelia', 'Neve' and 'W 14', where the highest assessment had the variety 'Venus'. Based on evaluation of peach varieties grown in commercial orchards the best variety was 'Symphonie', which achieved consistently high yields and is characterized by good health. 'Fidelia' and 'Orion' were chosen as a mediumly suitable varieties for commercial orchards.
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Genetická determinance dormance druhu Prunus armeniaca (L.)
Čechová, Jana
As achieving higher frost resistance is one of the apricot breeding goals in the Czech Republic, it is important to obtain a deeper understanding of the genetic background of the exit from endogenous dormancy for apricot flower buds. The reason is that frost resistance of flower buds is significantly reduced after exit from endogenous dormancy. The aim of this work was to contribute to the understanding of the process of exit of various plant tissues from dormancy, as the problem is very complex and containing a number of physiological processes that are controlled by the function and regulation of many various substances and corresponding genes. The time of exit of flower buds from endogenous dormancy was established by counting of flowering buds on sampled twigs after their transport to laboratory conditions. Furthermore, the production of ethylene, ethane, and CO2 was monitored for sampled twigs with flower and leaf buds. Other physiological parameters monitored during the course of this study were the level of abscisic acid in flower buds and their weigh during the sampling close to the period of exit from endogenous dormancy. An analysis of transcriptome using the cDNA-AFLP method was carried out on four apricot variants ('Sundrop', SEO, 'Vestra' a 'Betinka') to achieve a deeper understanding of the genetic background of exit of flower buds from endogenous dormancy. The transcription profiles obtained from this experiment were evaluated for changes in the expression profiles and fragments of genes with modified expression during the monitored period were sequenced identified. Obtained sequences were compared with sequences in electronic databases (NCBI and TIGR). The results of this comparison led to the identification of a number of the sequenced genes. The results of this study confirmed the suitability of use of the cDNA-AFLP method for the identification of gene candidates and getting a preliminary picture of the main molecular mechanisms taking place during the time of exit of flower buds from endogenous dormancy. The suitability of the used procedure was confirmed by the match between the genes identified from the sequencing and genes already described in the literature as being linked to the exit of plants from endogenous dormancy (e.g. gene coding for acquaporin, GTP-binding proteins, elongation factor 1 alpha, ubiquitin, and xyloglucan endotransglycosylase hydrolase). Measurements of concentration of selected substances during exit from endogenous dormancy do not allow definite conclusions about their influence on this process. On the other hand were identified several genes that might be candidates for markers identifying the output timing of endogenous dormancy of buds and provide a good starting point for further scientific research in this field.
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Mrazuodolnost ovocných dřevin
Prudil, Jakub
This bachelor thesis desribes principles of dormancy and frost hardiness of fruit trees; significant historical frost calamities in the Czech Republic; frost effects on fruit trees; relationship of phenophases and mikrophenophases from the perspective of evolution of the frost hardiness of fruit trees; the possibilities of protection against a late spring frosts and cryopreservation as a positive use of the effects of frost.
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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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