National Repository of Grey Literature 82 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Seasonal dynamics of physiological parameters of Norway spruce needles in mountain forest in relation to water balance of the forest site
Bednář, Pavel ; Albrechtová, Jana (advisor) ; Gebauer, Roman (referee)
Norway spruce (Picea abies (L.) Karst.) is an important economic tree species in the Czech Republic, which is currently significantly weakened and dying under the impacts of climate change. In young spruce forest stand in mountain region that was artificially established after the large-scale disturbance of forests in the mid-1990s, on the "U Dvou louček" research plot represented by a small forest catchment of an area of 32.6 ha, located in the upper part of the Orlické Mountains at an altitude of 880 - 920 m a.s.l., and in site conditions of predominantly Abieti-fageta piceae - water balance measurements were carried out during the 2019 and 2020 growing seasons. At the same time, during the mentioned two years, in total 6 samplings of biological material were carried out according to a standardized sampling methodology, and laboratory analyzes were carried out on this material. Laboratory analyzes were focused on three established age categories of needles, namely 1, 2, and 4 or more years old. The biophysical parameters of needles were determined based on the measurement of structural parameters and concentrations of photosynthetic pigments - chlorophyll a, chlorophyll b and total carotenoids from samples extracted in DMF using a laboratory spectrophotometer. Optical properties of the needles...
Structural modification of the root cortex in response to environmental conditions
Lehmannová, Justýna ; Tylová, Edita (advisor) ; Albrechtová, Jana (referee)
Plants encounter many adverse factors in their environment to which they must adapt in order to make effective use of their environment despite stresses such as water shortage, nutrient deficiency, soil salinization, soil compaction or flooding. This work focuses on the internal structure of the root and its changes in response to environmental stress conditions. Specifically, it focuses on structural modifications of the middle part of the root cortex, which play an important role in optimizing root system functions under stress conditions. It summarizes knowledge on the structure, mode of formation and regulatory mechanisms of aerenchyma formation, which is of great importance for plant survival under hypoxic conditions. These are encountered by many plants in flooded areas, including important agricultural crops such as rice and maize. This paper also analyses the role of aerenchyma in response to other stress factors such as nutrient deficiency, water deficit or substrate compaction. In addition, this work focuses on lesser-known structural modifications of the middle part of the cortex, whose function has not yet been fully understood, but which represent potentially important characteristics of the root system that could be the focus of future breeding of resistant crop cultivars. These...
The role of plant root exudates for soil carbon sequestration
Bourdais, Lukáš ; Albrechtová, Jana (advisor) ; Tylová, Edita (referee)
Global climate change is a process that affects us all today and will continue to affect us with increasing intensity in the future. An important way to reduce the concentration of CO2 in the atmosphere is the sequestration of carbon in pools other than the atmosphere, primarily in the soil pool. One way to achieve this is by increasing the carbon sequestration into the soil biomass using root exudates. Root exudates are released by plant roots into the soil to be beneficial to the plant and are also a good source of carbon for the rhizosphere (the soil in the immediate vicinity of the root system affected by its exudates). The rhizosphere is thus a suitable environment for microorganisms that play a major role in the soil carbon sequestration. In this thesis, I describe the composition and the role of root exudates for the plant, the importance of root border cells and border-like cells, the importance of exuded carbon coumpounds for microorganisms in the soil and their importance for carbon sequestration and CO2 mineralization in the soil. The role of root exudates and microorganisms in the soil carbon cycle is discussed with an emphasis on mineral-associated soil organic carbon and soil aggregates. This thesis also discusses the role of exudates for the rhizosphere priming effect and its...
Physiological, structural, and biochemical leaf traits of selected Poaceae species involved in oxidative stress protection and acclimation to different light conditions
Hunt, Lena Macrie ; Albrechtová, Jana (advisor) ; Lux, Alexander (referee) ; Šantrůček, Jiří (referee)
This thesis examines physiological, structural, and biochemical leaf traits in grasses (Poaceae family) and how they contribute to oxidative stress protection. Light is a major factor contributing both to oxidative stress in plants and the induction of protective mechanisms at the leaf level. The agriculturally important species barley (Hordeum vulgare) was used to investigate responses to varying irradiance and atmospheric CO2 levels. Barley was further used as a model organism to study the influence of different spectral qualities on oxidative protective mechanisms, particularly phenolic compound induction. This thesis also examines the protective leaf functional traits of wild grass species (Nardus stricta, Calamagrostis villosa, Molinia caerulea, and Deschampsia cespitosa) in a high-irradiance arctic-alpine tundra grassland. Phenolic compounds are important protective secondary metabolites in plants that protect against oxidative stress from high irradiance. This thesis evaluates phenolic compounds and their contributions to plant stress tolerance and introduces a novel method of quantifying the histochemical detection of phenolics in leaf cross-sections. Key results indicate that light quantity and quality play major influential roles in the accumulation of phenolic compounds. High irradiance...
How will a longer vegetative season affect carbon sequestration in plant biomass
Kasperová, Denisa ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
As a result of human activity, a large number of greenhouse gases, especially CO2, is released into the atmosphere, which causes a greater greenhouse effect and an increase in the temperature of the surface of the planet and the air in the atmosphere. Ongoing climate change is one of the great challenges facing society, as rising temperatures on the planet greatly affect the functioning of its ecosystems. Extremes arising from climate change, especially temperature rise and lack of precipitation or a change in the annual distribution of precipitation, affect the physiology and phenology of plants. Higher temperatures cause plant growing seasons to shift and lengthen, which has a direct impact on the sequestration of carbon in plant biomass through a biochemical, physiological plant process called photosynthesis. The increase in CO2 concentration in the atmosphere is slowed down by terrestrial forest ecosystems, as they can retain carbon in their tissues, especially in wood, for a relatively long time before it returns to the atmosphere. However, the efficiency of binding carbon into biomass also depends on other physiological processes, e.g., photorespiration, breathing, gas exchange between the plant and the atmosphere. Stressors caused by climate change can then limit growth, photosynthesis,...
The importance of root exudates for crop cultivation under climate change
Schnürer, Oliver ; Albrechtová, Jana (advisor) ; Tylová, Edita (referee)
Root exudates are compounds secreted by plant roots that can help plants, for example, to obtain nutrients from the soil or to increase their resistance to biotic stress. Root exudates can thus hide a great potential that can be used in agriculture. As human population grows, there is increasing pressure on agriculture, which must provide enough food to feed the global population, thus ensuring food security. Until now, agricultural activity has tried to satisfy this demand by intensification of agriculture, mainly by breeding highly productive crops when using intensive fertilizing, but the theoretical possible benefits of root exudates in breeding remained overlooked. Intensive farming practices can further exacerbate the impacts of ongoing climate change, for example by increasing soil carbon mineralization or reducing biodiversity. By using root exudates in the production of crops, it will be possible to achieve a higher nutrient content in soil, as well as a higher resistance of crops to pests, without the aforementioned negative impacts of intensive agriculture. In this work, I tried to describe the main functions of root exudates, their reaction to increased CO2 concentration in the atmosphere, their stress response caused by stressors of climate change and their theoretical use in...
Reproductive isolation barriers in the hybrid zone of the house mouse (Mus musculus)
Albrechtová, Jana ; Piálek, Jaroslav (advisor) ; Sedláček, František (referee) ; Reifová, Radka (referee)
Reproductive isolation occurring at the gamete level is called gametic isolation and almost always prevents gene flow between unrelated species and (to some extent) between closely related species or subspecies. The hybrid zone of the house mouse (HMHZ), which was formed by contact and interbreeding of two subspecies, the Western European house mouse (M. m. domesticus) and the Eastern European house mouse (M. m. musculus) provides a usefull model for the study of speciation processes involving gametic isolation. The probability of sperm competition within the female reproductive tract is high in the house mouse because high levels of sexual promiscuity (in 20˗40 % of all reproductive cycles) have been observed in this species. Thus, the reproductive isolation at gametic level may be determined both by the phenotypic characteristics of sperm (the ability to outcompete heterospecific sperm in the process of sperm- sperm competition) and by the preference of the sperm of conspecific males in the female reproductive tract (cryptic female choice). In my Ph.D. thesis I tested the degree of affinity of male and female gametes reciprocally between the both subspecies of M. musculus and the phylogenetically more distant species M. spretus, which is characterized by a higher degree of promiscuity. Although a...
Evaluation of the physiological status of European beech in its plantings on localities following the gradient of its ecological valence
Palouš, Daniel ; Albrechtová, Jana (advisor) ; Tomášková, Ivana (referee)
European beech (Fagus sylvatica L.) is one of the dominant tree species in Europe, presenting a keystone species for forest ecosystem functioning. The ongoing climate change alters the environmental conditions in the areas of the current distribution of European beech, leading to stress. Concerning the critical health status of forests in the Czech Republic and other European countries, it's even more urgent to monitor the health status of forests. For this, tools for early detection of a stand's physiological status decline are needed. The aforementioned tools can consist of indicators of the physiological status suggested by this thesis. This thesis aims to evaluate the applicability and sensitivity of the preselected set of indicators of the physiological status of European beech to the gradient of environmental conditions (temperature, precipitation) within its ecological valence. Four stands of European beech presenting the gradient of beech's ecological valence were observed over the peak of one vegetation season. Stand Kocanda presented the microclimatic and ecological optimum; stand Hradecko was on the lower margin of the altitudinal gradient of European beech distribution and presented the limit of low water availability; stand Deštné was on the upper margin of the altitudinal gradient of...

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