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Strukturně funkční charakteristika průduchů jmelí bílého (Viscum album L.) a jeho hostitele lípy (Tilia sp.)
Bělíček, Dominik
This thesis deals with a comparison of the morphology of the stomata of the hemiparasite European mistletoe (Viscum album L.) and its host lime tree (Tilia sp.) in the context of physiological parameters such as water potential, stomatal conductance, and photosynthesis, in order to understand the relationship between the two species. The research was carried out at the Ústřední hřbitov in Brno. Here, 10 infested and 10 uninfested lime trees were selected. During the summer of 2022, varnish impressions were taken from the leaves of lime and mistletoe trees and then all physiological parameters were measured. It was found that mistletoe infestation had almost no significant effect on both the morphology and physiology of lime tree leaves. Furthermore, it was shown that mistletoe has more smaller stomata than linden. It has been shown that although mistletoe has a higher stomatal conductance, the photosynthetic rate is the same for both species, thus the water use efficiency of mistletoe is much lower. It was confirmed that mistletoe, as a hemiparasite, has a much lower water potential than the host. Although this information helps to understand this interrelationship, it also results in further uncertainties worth to investigate in future.
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Reakce sazenic břízy bělokoré (Betula pendula Roth.) na stres suchem
Orlovský, Vít
Climate change, with its accelerating intensity, is the primary factor to which forest and urban stands need to respond. Particularly more frequently, recurrent periods of drought, coupled with rising average annual temperatures, mainly in urban development, represent a significant plant stressor. As silver birch (Betula Pendula Roth) is a frequently used tree in urban plantings, the aim of this work was to assess the physiological response of silver birch seedlings after the completed leaf development to stress by drought. Evaluation of the response of the seedlings to stress confirmed the assumption that water potential decreases as the drought increases. Due to the stress of the drought, we saw an 86% decrease in water potential measured at noon compared to the beginning of the experiment. From the results of a 17-day experiment, we found that stress from drought caused a 96% decrease in the rate of photosynthesis and stomatal conductance. So birch seedlings reacted very sensitively to drought stress by trying to avoid reducing water potential. When comparing the variability of the responses of individual seedlings, the physiological parameters showed a marked difference in their response to stress by drought. For example, for rate of photosynthesis, the coefficient of variation for stressed seedlings reached 97% at the end of the experiment. The PRI reflectance index, which indirectly characterises the carotenoid content, showed a coefficient of variation of even 306%. All this information provides us with clear evidence of the ability of individual birch seedlings to react to drought stress in a different way. Based on our measurements and subsequent results, we can conclude that the variability of silver birch seed material is able to respond to the demands implied by the projected climate change.
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The phenomenon of Foliar Water Uptake - mechanisms and consequences with a focus on temerate plant species
Oramová, Viktorie ; Lhotáková, Zuzana (advisor) ; Ponert, Jan (referee)
The ability of plants to absorb water through leaves has been a matter of the sientific discussion for a long time. Among the epiphytic species (tilandsies for example), reduced root system and foliar water uptake (FWU) is considered an adaptation for life in soil-less environment, and FWU is a necesssity. It was surprising, that the same ability has been discovered in plant species with normally developed root system. Over the time, new pieces of evidence about FWU in broad range of plant species has been published and FWU is getting universal for all plants, across the taxonomic groups or biomes, including temperate zone. The systematic focus on FWU and continuity of its research is lacking and therefore the knowledge about FWU is still only partial. This bachelor's thesis is focused on mechanisms of FWU and the leaf structures that may mediate it. The ability of water to pervade cuticle through aquatic pores is discussed, together with the possibility of water absorption by stomata, trichomes, hydathodes or epiphylic organisms. Another discussed topic is the use of this water by plant - improving of the water regime, refilling of the embolized xylem vessels, possible exudation by roots etc. The matter of FWU has other consequences on the ecosystem level, like in water cycle or the plant's...
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Vplyv veku na prieduchovú vodivosť a fotosyntézu dubu letného
Beňová, Eva
Increasing age brings along lowering of the tree vitality. Ecophysiological parameters as photosynthesis and its dependence on the concentration of CO2 (A-Ci curves) and light, chlorophyll fluorescence, stomatal conductance and water potential provide information on the physiological vitality of plants. These methods were used to assess the effect of age on the photosynthesis of pedunculate oak (Quercus robur). Two groups of trees were compared, the first group was over 600 years old while the second was less than 30 years old. Gas exchange measurements indicated lower light-saturated photosynthesis of old trees. Using A-Ci curves helped to estimate biochemical limitations of photosynthesis such as Vcmax, Jmax a Rd (maximum rate of carbon carboxylation, maximum electron transport speed and day respiration; respectively), which were similar for both groups of the trees. Chlorophyll fluorescence measurements enabled to estimate dark adapted (Fv/Fm) and light-adapted fluorescence (Fvˈ/Fmˈ). There were no differences between old and young trees in the parameters of chlorophyll fluorescence. However, the stomatal conductance was lower in old than in young trees under unlimited soil water availability. Resulting intercellular concentration of CO2 was lower in old trees, which indicated a lower concentration of CO2 at the sites of carboxylation and lower carbon assimilation rate. On the other hand, higher values of water potential of old trees in the mild drought in summer indicated their better access to soil water. Therefore, maximal stomatal conductance was similar in both groups of trees upon mild drought. Minimum stomatal conductance was higher in old trees. The results suggest that one of the reasons for the lowering of the vitality of old trees is their inability to regulate stomatal conductance, and to optimize carbon assimilation-water loss balance.
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Determination of water potential of selected plants grown in water deficit
Procházková, Denisa ; Hniličková, Helena (advisor) ; Martinková, Jaroslava (referee)
Bachelors thesis is processed on the topic Determination of water potential of selected plants grown in water deficit.
Tomatoes and peppers are thermophilic plants which are very prone to lack of moisture. Especially pepper which has smaller root system handles draught much worse. Both of these plants belong to the Solanaceae family.
This family is very important from the aspect of utility. It is because its fruits which can be consumed but they also need enough moisture for its growth. That is the reason why draught is on of the most stressful factors. The First objective of the experiment was to watch the process of the stressful reaction. The second objective was the evaluation of selected species.
The experiment took place in summer 2015 and it focused on young plants of tomatoes and peppers. These plants were exposed to controlled water stress in greenhouse which belongs to the Department of botany and plants physiology (University ČZU in Prague). During the experiment the plants have natural light cinditions a they were grown in containers with garden substrate. The experimental plants were devidet to two subgroups: first group was the controlled and the second was stressed. The first group was regulary watered but the second group has gradual cancellations of watering. Duration of the experiment was 14 days and it was ended after 7th collection when the plants were absolutely dehydrated. Water potential was measured by Dew point meter and mass huminidy was measured with machine called HH2 moisture meter.
The value of water potential with stressed group went down during the experiment. Initial values of Solanum lycopersicum were - 1,09 MPa and they were decreasing down to
- 4,07 MPa. Decreasing tendency was registered with the Capsicum annuum too which values were between - 1,02 MPa - 4,15 MPa. Values measured with stressed plants were lower than values measured with controlled group.
Mass huminidy with stressed plants was changing too. Reduction of soil huminindy was registered during measurement with both stressed species. Measured values were between 0,38 g.g-1 - 0 g.g-1 with Solanum lycopersicum and measured values with Capsicum annuum were between 0,55 g.g-1 - 0,01 g.g-1. When the value measured in stressed plants were lower than those in the control variant. Both species had simillar reaction with the water stress and they were not that different.
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Dynamika klíčení semen vybraných druhů dřevin ve vztahu k průběhu půdní vlhkosti a teploty na experimentální ploše v lokalitě Hurufa Shamena v Etiopii.
Veselský, Marek
The aim of the study was to compare the success rate of germination and survival rate of selected tree species with of soil moisture and temperature trough the course of time. 20 tree species (indigenous and non-indigenous) planted on an experimental plot in Hurufi Shamen, Ethiopia were tested for drought susceptibility and tolerance. Thesis includes an evaluation of the survival success rate of individual species. Two prospective species Acacia saligna with treatment and Dodonaea viscosa were found based on the information obtained. These species are able to survive on degraded soils and can be used for land recultivation through direct sowing in areas with similar natural conditions such as the location of the experimental area. The worst performance showed species Juniperus procera and Pinus patula.
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