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How is the leaf of a higher plant adapted to its photosynthetic function ?
Matušková, Eva ; Tichá, Ingrid (advisor) ; Nátr, Lubomír (referee)
4 Abstract Photosynthesis is a complex of complete biochemical processes which are working in photosynthetic structures, in our case in the leaf of higher plant. Leaf is the main photosynthetic organ of the higher plant which is excellently adapted to its photosynthetic function. Leaf used to be thin (short transport pathways) and used to have a big leaf area which enables to catch as much as possible of incoming irradiance. Light is falling to leaf epidermis. Epidermal cells do not contain chloroplasts and they represent a system of lenses which concentrate the light to the leaf mesophyll so that a light gradient appears. The cells of the palisade parenchyma are columnar and prolongated and the intercellular spaces enable the light going deeper into the leaf mesophyll. On the surface of the palisade parenchyma cells light is scattered and reflected and thus a significant proportion of down-welling light is sent back and will be absorbed for photosynthesis. The cells of spongy parenchyma have a very irregular shape and that amplifies multiple photon scattering. Important substrate for photosynthesis is a quantity of CO2. CO2 is in surrounding atmosphere and enters the leaf mainly through stomata what is the first barrier limiting CO2 flux into the leaf if the stomata are half-open or closed. Further on, CO2...
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Human impacts on ecosystems: appropriation of primary production and biodiversity in the Czech republic
Vačkář, David ; Moldan, Bedřich (advisor) ; Nátr, Lubomír (referee) ; Miko, Ladislav (referee)
The aim of this thesis is to explore relationship between selected indicators of human pressures and biological diversity in the Czech Republic. I assessed human impacts on ecosystems by calculating the fraction of aboveground net primary production appropriated by humans (aHANPP) in a cultural landscape of the Czech Republic. The human appropriation of aboveground net primary production reached 21.5 Tg C in aggregate or 56% of the potential natural productivity in 2006. I found the aHANPP to be a suitable indicator of human impacts on ecosystems as it detect trends and enables spatial mapping of human impacts. Furthermore, I tested hypothesis about a positive spatial relationship between human pressure indicators and biodiversity at species and ecosystem/landscape levels. I found a positive spatial coincidence (rs=0.361) of people (measured by human population density and extent of urban areas) and species richness (measured by richness of 10 taxonomic groups of vertebrates, invertebrates and plants). Although aHANPP was not related to species richness, diversity at the landscape level (measured by Shannon landscape diversity index) was significantly negatively related to the intensity of land and ecosystem use (indicated by aHANPP). The hump-shaped relationship is reflecting an intermediate disturbance...
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Genetically modified plants for future of globally warmed planet
Nedělová, Jana ; Opatrný, Zdeněk (advisor) ; Nátr, Lubomír (referee)
Many problems which have an adverse impact on crops, come into the agriculture with global warming the planet and thus changes in regional temperature and humidity regimes. These problems will be significant especially in developing countries that are already interfered by drought and threatened by famine. Therefore major target is developing of plants resistant to these climatic changes. Only the very classical breeding doesn't clearly sufficient for these tasks. However, genetic engineering could contribute significantly by genetically modified (GM) plants. This modern breeding-cultivation technology has several advantages in comparison with traditional breeding. One of them is for example targeted and well-controlled change in genotype, which allows obtaining plants with specific desired properties.
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Mesophyll CO2 conductance in consequence with the leaf anatomy and environmental factors.
Malcová, Kateřina ; Lhotáková, Zuzana (advisor) ; Nátr, Lubomír (referee)
The CO2 diffusion pathway from the atmosphere surrounding the leaf to the chloroplast stroma is composed of several parts, where each part poses certain resistance to the CO2 flux. The CO2 diffusion from the sub-stomatal cavities to the stroma is limited due to mesophyll conductance (gm), which includes CO2 movement in gas, liquid and lipid phases. The mesophyll conductance is influenced by factors that are both internal (e.g. leaf anatomy and leaf age) and external (e.g. irradiance, temperature). Internal factors exhibit rather long-term responses of gm, while external factors are involved in short-term changes. For these rapid changes are probably responsible aquaporins. gm significantly influences the rate of net photosynthesis, almost in the same range as a stomatal conductance does. The limitation of photosynthesis given by mesophyll conductance is not fixed and varies among species and plant functional groups. Due to continual increase of CO2 concentration in the atmosphere, variability in gm can lead to enhanced competitive potencial of some plant species.
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Human impacts on ecosystems: appropriation of primary production and biodiversity in the Czech republic
Vačkář, David ; Moldan, Bedřich (advisor) ; Nátr, Lubomír (referee) ; Miko, Ladislav (referee)
The aim of this thesis is to explore relationship between selected indicators of human pressures and biological diversity in the Czech Republic. I assessed human impacts on ecosystems by calculating the fraction of aboveground net primary production appropriated by humans (aHANPP) in a cultural landscape of the Czech Republic. The human appropriation of aboveground net primary production reached 21.5 Tg C in aggregate or 56% of the potential natural productivity in 2006. I found the aHANPP to be a suitable indicator of human impacts on ecosystems as it detect trends and enables spatial mapping of human impacts. Furthermore, I tested hypothesis about a positive spatial relationship between human pressure indicators and biodiversity at species and ecosystem/landscape levels. I found a positive spatial coincidence (rs=0.361) of people (measured by human population density and extent of urban areas) and species richness (measured by richness of 10 taxonomic groups of vertebrates, invertebrates and plants). Although aHANPP was not related to species richness, diversity at the landscape level (measured by Shannon landscape diversity index) was significantly negatively related to the intensity of land and ecosystem use (indicated by aHANPP). The hump-shaped relationship is reflecting an intermediate disturbance...
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How is the leaf of a higher plant adapted to its photosynthetic function ?
Matušková, Eva ; Nátr, Lubomír (referee) ; Tichá, Ingrid (advisor)
4 Abstract Photosynthesis is a complex of complete biochemical processes which are working in photosynthetic structures, in our case in the leaf of higher plant. Leaf is the main photosynthetic organ of the higher plant which is excellently adapted to its photosynthetic function. Leaf used to be thin (short transport pathways) and used to have a big leaf area which enables to catch as much as possible of incoming irradiance. Light is falling to leaf epidermis. Epidermal cells do not contain chloroplasts and they represent a system of lenses which concentrate the light to the leaf mesophyll so that a light gradient appears. The cells of the palisade parenchyma are columnar and prolongated and the intercellular spaces enable the light going deeper into the leaf mesophyll. On the surface of the palisade parenchyma cells light is scattered and reflected and thus a significant proportion of down-welling light is sent back and will be absorbed for photosynthesis. The cells of spongy parenchyma have a very irregular shape and that amplifies multiple photon scattering. Important substrate for photosynthesis is a quantity of CO2. CO2 is in surrounding atmosphere and enters the leaf mainly through stomata what is the first barrier limiting CO2 flux into the leaf if the stomata are half-open or closed. Further on, CO2...
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