Národní úložiště šedé literatury Nalezeno 64 záznamů.  1 - 10dalšíkonec  přejít na záznam: Hledání trvalo 0.00 vteřin. 
Využití růstových modelů k hodnocení způsobů hospodaření při pěstování polních plodin a vlivu na půdní procesy
Hlavinka, Petr ; Trnka, Miroslav ; Balek, Jan ; Dubrovský, Martin ; Pohanková, Eva ; Wimmerová, Markéta ; Žalud, Zdeněk
Metodika popisuje možnosti aplikace růstových modelů k hodnocení různých způsobů hospodaření v rámci pěstování vybraných polních plodin a jejich vliv na vybrané půdní procesy a podmínky. Tato publikace se zaměřuje na komplexní simulace v interakčním systému půda-rostlina-atmosféra-zemědělec pomocí modelu HERMES. Schopnost simulovat procesy v podmínkách střídání plodin kontinuálně a nepřerušeně (i pro období delší než 100 let) přináší možnost poukázat na dlouhodobé trendy ve vývoji půdních procesů. Dále je možné srovnávat důsledky rozdílných přístupů hospodaření v kombinaci s vybranými stanovištními a půdními podmínkami a také pro vybrané scénáře vývoje klimatu. V rámci této publikace jsou prezentovány výstupy pro podmínky bez předpokládané změny klimatu i podmínky reflektující posun klimatických podmínek v průběhu 21. století na základě 6 vybraných klimatických scénářů. Pro vybrané kombinace podmínek jsou také kvantifikovány předpokládané dopady na růst a výnosy cílové skupiny plodin.
Foliar application of zinc reduces the risk of drought stress on poppy (Papaver somniferum L.)
Škarpa, P. ; Richter, R. ; Hlavinka, Petr ; Trnka, Miroslav
Especially in arid regions, drought stress is considered as one of the main reasons for yield reduction of plant. Zinc, as one of the essential microelements in crop plant, plays a crucial role in resistance to drought stress. The objective of the vegetation experiment established in 2011-2015 on locality Zaboice was to explore the effect of the foliar zinc application on the yield of poppy in interactions with weather conditions observed years. Effect of zinc foliar application was significantly dependent on the average daily air temperature (r =-0.936). Foliar application of zinc increases production of poppy seed, in the range from 6.9 to 25.5 % and the efficiency of zinc foliar fertilization increases with a widening deficit rainfall calculated as the difference between the precipitation sum and reference evapotranspiration of poppy growing season (r =-0.9072). In general, the results of the present study indicate that usage of zinc foliar application reduces the harmful effects of water deficit stress and increases resistance to drought stress in poppy plant.
Evaluating drought risk for permanent grasslands under present and future climate conditions
Trnka, Miroslav ; Schaumberger, A. ; Formayer, H. ; Eitzinger, Josef ; Hlavinka, Petr ; Semerádová, Daniela ; Dubrovský, Martin ; Možný, M. ; Thaler, S. ; Žalud, Zdeněk
Over the past years, the changing climate has affected parts of Czech Republic and Austria by drought spells of the intensity and extend that was unprecedented in previous decades. These events had a significant impact on agricultural areas, especially on the grasslands. The idea behind the GIS monitoring relies on hypothesis that the effect of weather and climate conditions on the grassland production can be estimated by models that describe certain natural processes in a simplified manner and in spatialized form.
Využití předpovědi půdní vlhkosti a intenzity sucha pro lepší rozhodování v rostlinné výrobě
Trnka, Miroslav ; Štěpánek, Petr ; Chuchma, F. ; Možný, M. ; Bartošová, Lenka ; Hlavinka, Petr ; Balek, Jan ; Zahradníček, Pavel ; Skalák, Petr ; Farda, Aleš ; Semerádová, Daniela ; Meitner, Jan ; Bláhová, M. ; Fiala, R. ; Žalud, Zdeněk
Metodika popisuje způsob přípravy předpovědi půdní vlhkosti a intenzity a sucha a současně se zabývá tím, jak jsou tyto předpovědi spolehlivé a jak mohou být využívány. Schopnost předpovídat hodnoty půdní vlhkosti s výhledem až na 9 dní pomocí souboru modelů pro numerickou předpověď počasí sebou nese i nové možnosti reakce v oblasti zemědělského hospodaření. S ohledem na poměrně vysokou míru předpověditelnosti jak půdní vlhkosti i intenzity sucha metodika představuje základní postupy, které je možné využít pro přijetí vhodných opatření od využití závlah po extenzifikaci produkce. V rámci této publikace jsou pak jako příklad prezentovány výsledky analýzy úspěšnosti předpovědi zpracovávané v reálném čase v roce 2017. Prezentovaný systém je plně funkční a využitelný i pro následující sezóny na portále www.intersucho.cz.
Effect of artificially induced drought on growth and productivity of selected crops within field experiment in Bohemian-Moravian highlands
Wimmerová, Markéta ; Hlavinka, Petr ; Trnka, Miroslav ; Žalud, Zdeněk ; Pohanková, Eva
The field experiments based on manipulating the crop environment are critical for determining the crop’s response to the climatic conditions expected in the future. An experimental site in Domanínek is located by 49°31'42 N, 16°14'13 E at an altitude of 560 m (potato production area). The field experiment using rain-out shelters for soil water availability reduction was conducted in 2015/2016. The main aim of this study was to assess the impacts of different water availability (rain-out shelters vs. control) on the performance of selected field crops (spring barley, winter wheat, winter rape and silage maize). Reduction of precipitation in treatment with rain-out shelters was confirmed by measuring soil water content. The amount of precipitation during growing period was reduced by 251 mm, 277 mm, 217 mm and 240 mm for the spring barley, winter wheat, winter rape and silage maize, respectively. As a consequence, leaf area index and yields declined, however the crop responses were not consistent.
Towards a combining of remote sensing and in situ evapotranspiration measurements
Fischer, Milan ; Jurečka, František ; Anderson, M. ; Hain, C. ; Pozníková, Gabriela ; Hlavinka, Petr ; Orság, Matěj ; Lukas, V. ; Žalud, Z. ; Trnka, Miroslav
This study provides preliminary results from combining in situ Bowen ratio energy balance (BREB) and\nevapotranspiration (ET) measurements techniques with physically based remote sensing ET estimates determined\nby the Atmosphere-Land Exchange Inverse (ALEXI) model. Evapotranspiration measurements\nand ALEXI estimates were analysed in an agricultural area close to Polkovice, Czech Republic during 2015,\nwhen a drought spell and intensive heatwaves appeared in the country. The BREB system was monitoring a\nwinter wheat (Triticum aestivum L.) field (~26 ha) while the ALEXI pixel (~5 km resolution) covered a wide\nrange of crops, including mainly winter wheat, spring barley, and winter rape. The study results showed that,\nalthough the applied methods work at different spatial scales (field vs. landscape), their combination can provide\nfurther insights into ET at both scales. For instance, such approach can be used to identify whether a specific\necosystem investigated in situ contributes to cooling or warming of the landscape.
Application of multispectral remote sensing indices for sensing indices for estimating crop yields at field level
Jurečka, František ; Lukas, Vojtěch ; Hlavinka, Petr ; Semerádová, Daniela ; Fischer, Milan ; Žalud, Zdeněk ; Trnka, Miroslav
Remote sensing can be used for yield estimation prior to harvest and can replace or complement classical\nways of estimating crop yields. This study was undertaken in Polkovice, located in the Czech Republic’s\nHaná region. For 2015 and 2016, two data sets of satellite imagery were used: the Moderate Resolution\nImaging Spectroradiometer and the Landsat 8. Vegetation indices from satellites were compared with crop\nyields at the level of land blocks. Winter wheat and spring barley yield data, representing crops planted\nover the analysed period, were used for the comparison. The results of the index–yield comparison showed\nthat vegetation indices from remote sensing data provide reliable information for yield estimation prior to\nharvest. Indices are also able to evaluate the spatial variability of a crop within the field. The results showed\nthat remote sensing data need to have detailed spatial resolution in order to provide reasonable information\nabout yield at such a detailed level.
Potential of flux-variance and surface renewal methods for sensible heat flux measurements at agricultural and forest surfaces
Fischer, Milan ; Katul, G. ; Pozníková, Gabriela ; Noormets, A. ; Domec, J.-C. ; Trnka, Miroslav ; King, J.
Two alternative micrometeorological methods, flux-variance (FV) and surface renewal (SR), based on\nmeasurements of high-frequency temperature fluctuation and Obukhov length stability parameter, were\ntested against eddy covariance (EC) sensible heat flux (H) measurements. The study was conducted at\nthree sites representing agricultural, forestry, and agroforestry systems. In terms of measurement setup,\nthese sites represented surface, roughness, and canopy top layer, respectively. As expected, the best match\nof all the methods was in the surface layer, whilst it was poorer in the roughness and canopy sublayers.\nSystematic deviation from EC across all three investigated surfaces was within 16% and 8% for FV and SR,\nrespectively. While FV resulted in higher correlation with EC measurements (0.93–0.98 vs. 0.89–0.97),\nSR provided less systematic biases (1.02–1.08 vs. 0.94–1.16). In general, both FV and SR provided slightly\nhigher H as compared to EC. We suggest that parallel deployment of FV and SR is useful, as both methods\nrequire the same instrumentation yet they are based on sufficiently different theories. Therefore, the agreement\nbetween FV and SR increases confidence in the results obtained and vice versa.
Comparison of leaf area index dynamics and radiation use efficiency of C3 crops in the Czech Republic
Tripathi, Abishek ; Pohanková, Eva ; Trnka, Miroslav ; Klem, Karel
Leaf area index (LAI) and radiation use efficiency (RUE) are key parameters for plant growth and productivity.\nBecause of irregularities in weather conditions, accurate estimation of crop production requires\nunderstanding relationships between weather, LAI, RUE, and final production. It is thus important to\nstudy how the LAI dynamics, leaf area duration (LAD), and RUE are related to aboveground biomass production\nfor different crops. In our study, we compared aboveground dry mass production, LAI dynamics,\nRUE, and LAD in three C3 crops (spring barley [SB], winter wheat [WW], and oilseed rape [OSR]) in the\nCzech Republic. LAI was measured on the basis of transmitted photosynthetically active radiation, LAD\nwas calculated by counting the number of days in the growing season, RUE was measured using Beer’s\nlaw, and the aboveground dry mass was estimated at the time of harvest. Results of our study showed high\nbiomass production and RUE in SB while there was highest maximum LAI (LAImax) and LAD in OSR. We\nconcluded that LAI dynamics or LAImax do not fully reflect the crop production and that RUE may be considered\nas a better indicator for aboveground dry mass production.
Water-use efficiency of winter wheat under heat and drought stress
Hlaváčová, Marcela ; Klem, Karel ; Novotná, Kateřina ; Rapantová, Barbora ; Urban, Otmar ; Hlavinka, Petr ; Smutná, P. ; Horáková, V. ; Škarpa, P. ; Trnka, Miroslav
Because such extreme weather events as dry spells and heat waves are expected to occur more frequently\ndue to climate change, the issue of appropriate water management for sustainable agricultural production\nis increasingly important. This study focuses on wheat, the second most widely grown cereal in the world\nand the most common cereal in European countries. The study assesses the effects of short periods (3 and\n7 days) of high temperatures (26°C as a control, 32°C, 35°C, and 38°C as daily temperature maxima from\n12:00 to 14:00) and drought stress at different developmental stages (DC 31 – beginning of stem elongation,\nDC 61 – flowering, and DC 75 – early grain filling) on water-use efficiency (WUE) in winter wheat\ncultivar Tobak. This cultivar is one of the most widespread winter wheat cultivars in Czech Republic fields.\nThe analysis of WUE showed that the cv. Tobak plants were able to withstand drought stress conditions\nthrough increased WUE. In contrast, wheat plants were stressed more markedly if exposed to higher temperatures\nand drought in combination. Generally, the wheat plants were most sensitive to drought at DC\n31.

Národní úložiště šedé literatury : Nalezeno 64 záznamů.   1 - 10dalšíkonec  přejít na záznam:
Chcete být upozorněni, pokud se objeví nové záznamy odpovídající tomuto dotazu?
Přihlásit se k odběru RSS.