Národní úložiště šedé literatury Nalezeno 12 záznamů.  1 - 10další  přejít na záznam: Hledání trvalo 0.01 vteřin. 
Metody hodnocení potenciální zranitelnosti podzemních vod reaktivním dusíkem při pěstování polních plodin na orné půdě
Zemek, František ; Pikl, Miroslav ; Holub, Petr ; Klem, Karel ; Záhora, J. ; Vavříková, J.
Metodika identifikace potenciálního průsaku reaktivního dusíku do podzemních zdrojů vod je založena na hodnocení kombinace konzervativních, těžko měnitelných a časově stabilních faktorů povodí a těch faktorů, které může člověk svým působením v krajině ovlivňovat. K ním patří způsoby a intenzita pěstování polních plodin na orné půdě povodí. Parametry druhé skupiny jsou získávány na základě metod obrazové spektroskoie leteckých hyperspektrálních a satelitních multispektrálních dat Sentinel-2.
Effect of nutrients deficiencies on root architecture and growth of winter wheat
Rattanapichai, W. ; Klem, Karel
The study of the effects of N, P, K deficiencies on root architecture and growth was tested in phenotyping platform with winter wheat (Bohemia variety). The experiment was arranged with 4 treatments: Complete nutrient, Without N, Without P and Without K. The root were grown on the surface of vertically fixed black filter paper sheets (30x60cm), covered from both sides by black plastic sheets (PVC-P). The system was setup with a micro-irrigation channel in the top of sheets to ensure circulation of hydroponic medium as hydroponic system. Eighteen days after transplanting, we took the root images by the standard RGB digital camera. To evaluate the root architecture parameters the "SmartRoot" software was used. The results showed that nutrient deficiency had effect on root architecture of winter wheat. N deficiency increase in total seminal root and lateral root length and root/shoot ratio, while P deficiency resulted in increase of mean root diameter, total root area when compared to the control. N deficiency also decreased root and shoot dry weight and total leaf area. However, nutrient deficiency slightly decreased lateral density. There was a slight effect of K deficiency on root architecture when compared to the complete nutrient application. The increasing of leaf dry weight was related with the increased of root dry weight.
Effect of temeperature stress and water shortage on thousand grain weight of selected winter wheat varietes
Hlaváčová, Marcela ; Pohanková, Eva ; Klem, Karel ; Trnka, Miroslav
The aim of the presented study was to assess the effect of high temperatures and water shortage during anthesis on thousand grain weight (TGW) of two winter wheat varieties (Tobak and Pannonia). In addition, numbers of grains per spike were also assessed. The six growth chambers were used to simulate heat stress conditions within following gradient of temperature maxima: 26 degrees C (control chamber), 29, 32, 35, 38 and 41 degrees C. The relative humidity (RH) course and photosynthetically active radiation (PAR) intensity were controlled via protocols. Additionally, drought stressed (dry) and well-watered (wet) treatments were established within each growth chamber. The plants were removed from the growth chambers after 14 days and they were left until a full maturity, exposed to actual weather conditions. The TGW at 14% moisture were evaluated for particular treatments within both winter wheat varieties. TGW was generally more affected by high temperatures under drought stress than in well-watered conditions. The results revealed that Pannonia TGW was much more affected by the water deficiency in combination with high temperature (particularly 38 and 41 degrees C) than Tobak TGW.
Effect of high temperature and water shortage stresses duration during anthesis on the selected winter wheat yield formation components
Hlaváčová, Marcela ; Rapantová, Barbora ; Novotná, Kateřina ; Klem, Karel ; Hlavinka, Petr ; Trnka, Miroslav
The aim of this study was to assess the effect of drought and high temperatures on Tobak winter wheat variety during one of the most sensitive developmental stage (anthesis) from the viewpoint of harvest index (HI) and spike productivity (SP). The 5 growth chambers (where the plants were exposed to these stress factors) were used for these purposes. The various protocols consisting in photosynthetically active radiation (PAR) course, relative air humidity (RH) and daily temperature courses were run. The plants were divided into 2 groups within each growth chambers: (1) Drough-stressed (Dry) and (2) well-watered (Wet). Two lengths of stresses duration were tested: 3 and 7 days. The plants were exposed to ambient weather conditions up to the full maturity after stresses exposition within the growth chambers. Subsequently, the plants were harvested manually and HI and SP were evaluated. The statistical analyses showed that the effect of each stress factor separately was statistically significant both for HI and SP14, nevertheless, these two factors interaction was statistically significant only in the case of HI.
Effect of drought stress on selected winter wheat yield formation components within pot and field experiimental design
Hlaváčová, Marcela ; Pohanková, Eva ; Klem, Karel ; Hlavinka, Petr ; Trnka, Miroslav
The object of this study was to find out what is the behaviour of the same winter wheat variety (Bohemia) plants cultivated within pot and field experiment. Therefore, the main aim of this study was to verify (based on the pot experiment results) whether the pot experiment (that is limited by the soil area) does not substantially affect plant reactions. The pot experiment was carried out in growth chambers where daily temperature course, relative humidity (RH) and photosynthetically active radiation (PAR) were set via protocols. The pots were exposed to the drought stress for 14 days with the daily maximum temperature 26 °C from noon to 2 p.m. The pots were split into 2 groups: (1) Dry where the soil moisture within pots were maintained below 30% of the maximum water holding capacity, (2) Wet where the soil moisture did not decrease below 70% of the maximum water holding capacity. The plants within Wet variant were considered as a control group. The pots were placed onto the concrete floor of a vegetation hall (where the plants were exposed to the weather conditions) prior and after stress regime exposition. The field experiment was conducted within experimental station in Bystřice nad Pernštejnem belonging to the Bohemian-Moravian Highlands in the Czech Republic. The drought stress was established through the transparent roofs installed above plants’ tops level in the field. The control experimental plot without roofs was nearby there as well. The plants were harvested when the full maturity was reached and the selected yield formation components were evaluated.
Vliv vysokých teplot a různých vodních režimů na tvorbu nadzemní biomasy vybraných odrůd pšenice ozimé
Hlaváčová, M. ; Klem, Karel ; Hlavinka, Petr ; Trnka, Miroslav
Cílem této studie bylo hodnocení vlivu vysoké teploty a nedostatku půdní vláhy v období kvetení na alokaci nadzemní biomasy dvou odrůd pšenice ozimé (Bohemia a Pannonia). Za tímto účelem byly simulovány podmínky stresu teplem s těmito teplotními maximy: 26 °C (kontrolní komora), 29, 32, 35, 38 a 41 °C. Průběh relativní vlhkosti vzduchu (RV) a fotosynteticky aktivní radiace (FAR) byl řízen prostřednictvím protokolů. Kromě toho byla v každé komoře ustanovena varianta stresovaná suchem (Dry) a varianta optimálně zalévaná (Wet). Rostliny byly po 14 dnech stresového režimu vyjmuty z komor a do období plné zralosti byly vystaveny vlivům aktuálního počasí. Po sklizni byla pro všechny varianty nastolených stresových podmínek obou odrůd vyhodnocena produktivita hlavních klasů a sklizňový index (HI) hlavních klasů
The effect of drought and nitrogen fertilization on the production, morphometry, and spectral characteristics of winter wheat
Trunda, Petr ; Holub, Petr ; Klem, Karel
Methods of study based on the spectral reflectance of vegetation are now commonly used in researching both natural ecosystems and field crops.The aims of this experiment were to evaluate the effect of drought and nitrogen (N) fertilization on N use efficiency in winter wheat and use the obtained spectral characteristics to assess stand heterogeneity as a potential consequence of different crop nutrition. Twelve experimental plots of winter wheat were manipulated to drought from 8 May 2013 to 12 June 2013. The effect of drought was observed in two treatments: control without fertilization (N0; 0 kg N ha−1) and N fertilization (N140; 140 kg N ha–1). Plant samples were then taken for determination of above-ground biomass and N content in dry matter. Spectral characteristics of wheat were measured in the earing phase at canopy level. The effect of drought on the morphometric parameters of winter wheat was statistically significant only on N-fertilized plots (N140). Total above-ground biomass decreased by a significant 18% in the N140 treatment as a result of the simulated drought. This decrease was reflected in statistically significant reductions of all individual plant parts (stems, leaves, spikes) in N140. Responses to drought stress were observed in many vegetation indices, particularly in NDVI, GNDVI, and WI/NDVI. The results show there are significant relationships between N content in the grain and vegetation indices. A quite marked separation was observed in the relationships between dry and ambient treatments for vegetation indices NRERI, TCARI/OSAVI, VOG2 and GM. Generally, the impact of drought increased at higher levels of N content in the grain, which corresponded with the results of morphometric analysis. Use of reflectance in the study of vegetation and field crops regarding risk assessment of mineral N leaching from soils has considerable potential especially in mapping large areas and monitoring temporal changes relating to N release.
Interactive effects of elevated CO2 concentration, drought, and nitrogen nutrition on yield and grain quality of spring barley and winter wheat
Novotná, Kateřina ; Rajsnerová, Petra ; Veselá, Barbora ; Klem, Karel
The interactive effects of elevated CO2 concentration (EC; 700 μmol mol–1), drought stress, UV exclusion, and nitrogen nutrition were studied in open-top chambers located in the Bohemian–Moravian highlands (24 in total). Above-ground biomass at the time of harvest, grain yield, and grain quality parameters were studied in winter wheat (variety Bohemia) and spring barley (variety Bojos). The results showed that elevation of CO2 concentrations increased above-ground biomass and grain yield. Higher levels of nitrogen increased the stimulatory effect of EC on above-ground biomass and grain yield. In addition, UV exclusion stimulated the effect of EC. EC generally led to increased rates of photosynthesis and assimilate formation. Increased storage of starch in the grain led to an unbalanced proportion of proteins and a decrease in their relative content in grain. Similarly to grain yield and above-ground biomass, the decrease in protein content under EC was also more pronounced under UV exclusion. EC led also to reduction of other quality parameters, such as the Zeleny sedimentation test. This effect is more pronounced when nitrogen is not a limiting factor as well as under the effect of drought. The stronger effect under drought stress is probably due to increased water use efficiency.
Interactive effects of UV radiation and drought on the accumulation of flavonols in selected herbs and grass in a mountain grassland ecosystem
Veselá, Barbora ; Novotná, Kateřina ; Rajsnerová, Petra ; Klem, Karel ; Holub, Petr ; Urban, Otmar
The main objective of this 4-year experiment conducted in a mountain grassland ecosystem was to investigate the interactive effects of ultraviolet (UV) treatment and drought on changes in accumulation of UV-screening compounds (flavonols) in selected herbs (Hypericum maculatum Crantz, Rumex obtusifolius L.) and grass (Agrostis tenuis Sibth.). Inasmuch as drought and UV radiation induce similar protective mechanisms, we tested the hypothesis that UV radiation and drought elicit synergistic effects on flavonol accumulation. The experimental plots were manipulated using rainout shelters enabling the exclusion and transmission of incident precipitation and UV radiation. Generally, UV and drought treatments had similar effects on flavonol accumulation. For R. obtusifolius, UV exclusion resulted in a substantial reduction of UV-screening compounds, particularly under ambient precipitation conditions, while for H. maculatum and A. tenuis UV exclusion caused only a slight reduction of flavonol content. Similarly, the drought treatment caused an increase in flavonol accumulation.
Convergence of morphological, biochemical, and physiological traits of upper and lower canopy of European beech leaves and Norway spruce needles within altitudinal gradients
Rajsnerová, Petra ; Klem, Karel ; Večeřová, Kristýna ; Veselá, Barbora ; Novotná, Kateřina ; Rajsner, Lukáš ; Holub, Petr ; Urban, Otmar
Climatic variation along altitudinal gradients provides an excellent natural experimental set-up for investigating the possible impacts of climate change on terrestrial organisms and ecosystems. The present work has explored for the first time the acclimation of upper versus lower canopy leaves or needles in European beech (Fagus sylvatica) and Norway spruce (Picea abies) forests along an altitudinal gradient. We tested the hypothesis that restrictive climatic conditions associated with high altitudes reduce within-canopy variations of leaf traits. The investigated beech and spruce forests were located on the southern slope of the Hrubý Jeseník Mountains (Czech Republic). All measurements were taken on leaves from the upper and lower parts of the canopy of mature trees (>60 years old) growing at low (400 m a.s.l.), middle (720 m a.s.l.), and high (1,100 m a.s.l.) altitudes. Generally, we observed that with increasing altitude, which is associated with adverse microclimatic conditions, a convergence of CO2 assimilation rate and other physiological, morphological, and biochemical characteristics between the upper and lower canopy occurred. However, differences in altitudinal response among individual traits and species were found. Such plasticity in acclimation of leaves and needles has the potential to cause substantial change in the photosynthesis of individual parts of forest canopies within the vertical profile and their contribution to the overall carbon balance of vegetation.

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