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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.
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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.
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Drought monitor for the Czech Republic-www.intersucho.cz
Trnka, Miroslav ; Hlavinka, Petr ; Semerádová, Daniela ; Balek, Jan ; Možný, M. ; Štěpánek, Petr ; Zahradníček, Pavel ; Hayes, M. ; Eitzinger, Josef ; Žalud, Zdeněk
Because drought and its impacts are among the worst hydrometeorological extremes (including also Central European conditions), the aim of this paper is to describe the core and use of the Integrated drought monitoring system for the Czech Republic. Land-use, information about soil, vegetation characteristics and meteorological data are used as inputs to validated water balance SoilClim model, which is applied for estimates of actual and reference evapotranspiration and water saturation of the soil profile in % or soil moisture content in mm. Moreover the prognosis of expected soil moisture (based on probabilistic analysis) is calculated for next 1, 2, 4 and 8 weeks. Main results are weekly updated in form of drought occurrence maps, which are published in spatial resolution 500 m for whole territory of the Czech Republic and for all its 76 districts separately. Final maps with detail comments are available at drought topic dedicated web page (ANONYM 3 2014).
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Assessing the impact of drought stress on winter wheat canopy by hermes crop growth model
Wimmerová, Markéta ; Pohanková, Eva ; Kersebaum, K. C. ; Trnka, Miroslav ; Žalud, Zdeněk ; Hlavinka, Petr
The main aim of this study was evaluate a drought stress effect on winter wheat development, growth (leaf area index), soil moisture and yields. Simultaneously, the ability of Hermes crop growth model to simulate drought stress response was tested. The field trial was established at Domanínek station (Bystřice nad Pernštejnem district, Czech Republic) in 2014. Mobile rain-out shelters for precipitation reduction were installed on the plots of winter wheat in May 2015. Results of this study showed that model is able to reproduce well a soil moisture content and to certain extent the drought stress for grain yields of winter wheat. Using the rain-out shelters (from 19 May to harvest on 6 August 2015), real winter wheat yields were reduced by 1.7 t/ha. The model was able to estimate the average yield with a deviation of 0.15 t/ha (6%) for no stressed variant. Model underestimated the yields for sheltered variant with a difference 0.67 t/ha (71%) on average against observed yields.
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Reliability of regional crop yield predictions in the Czech Republic based on remotely sensed data
Hlavinka, Petr ; Semerádová, Daniela ; Balek, Jan ; Bohovič, Roman ; Žalud, Zdeněk ; Trnka, Miroslav
Vegetation indices sensed by satellite optical sensors are valuable tools for assessing vegetation conditions including field crops. The aim of this study was to assess the reliability of regional yield predictions based on the use of the Normalized Difference Vegetation Index and the Enhanced Vegetation Index derived from the Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite. Data available from the year 2000 were analysed and tested for seasonal yield predictions within selected districts of the Czech Republic. In particular, yields of spring barley, winter wheat, and oilseed winter rape during 2000–2014 were assessed. Observed yields from 14 districts were collected and thus 210 examples (15 years within 14 districts) were included. Selected districts differ considerably in soil fertility and terrain configuration and represent a transect across various agroclimatic conditions (from warm/dry to relatively cool/wet regions). Two approaches were tested: 1) using 16-day temporal composites of remotely sensed data provided by the United States Geological Survey, and 2) using daily remotely sensed data in combination with an originally developed smoothing method. Yields were predicted based on established regression models using remotely sensed data as an independent parameter. In addition to other findings, the impact of severe drought episodes within vegetation was identified and yield reductions at a district level were predicted. As a result, those periods with the best relationship between remotely sensed data and yields were identified. The impact of drought conditions as well as normal or above-normal yields of the tested field crops were predicted using the proposed method within the study region up to 30 days prior to harvest.
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Interactive effects of elevated CO2 concentration, drought, and nitrogen nutrition on yield and grain quality of spring barley and winter wheat
Surá, 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.
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The influence of reduced precipitation supply on spring barley yields and the ability of crop growth models to simulate drought stress
Pohanková, Eva ; Orság, Matěj ; Hlavinka, Petr
This paper evaluates the first year (2014) of results from a field experiment with spring barley (cultivar Bojos) under reduced precipitation supply. The field experiment was carried out at an experimental station in the Czech Republic and consisted of small plots in two variants and three repetitions. The first variant was uncovered, and the second was partly covered to exclude rain throughout the entire vegetation season. For plots’ partial covering, a material was used to divert rainwater away from 70% of the plots. The main aim was to determine whether there are any differences in soil water content or in grain yield size between uncovered and partly covered plots and to compare the results obtained. Data measured in this field experiment were used to compare simulations of this field experiment in the DAISY crop growth model. Subsequently, the crop growth model’s ability to simulate grain yield, which was affected by drought stress, was explored. In reality, differences in phenological development and grain yield size were not evident. Reducing precipitation supply in DAISY by about 70% led to simulations of covered plots with reduced grain yield in accordance with the initial hypothesis. Agreement between observed and simulated grain yield was evaluated using selected statistical indicators: root mean square error (RMSE) as a parameter of average magnitude of error and mean bias error (MBE) as an indicator of systematic error. RMSE of grain yield was 2.6 t ha−1. MBE revealed grain yield undervalued by 2.6 t ha−1.
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Aplikace růstových modelů pro lokální hodnocení dopadů změny klimatu na vybrané plodiny
Hlavinka, Petr ; Trnka, Miroslav ; Balek, Jan ; Dubrovský, Martin ; Pohanková, Eva ; Žalud, Zdeněk
Metodika je zaměřena na přehledný popis problematiky využití specializovaných softwarových nástrojů nazývaných růstové modely s důrazem na jejich aplikaci pro hodnocení dopadů změny klimatu na lokální úrovni. Ambicí této publikace je seznámit čtenáře se stručnou historií vývoje růstových modelů, jejich členěním, aktuálními trendy jejich vývoje a využití, ale v první řadě prezentovat metody přípravy vstupních databází, prvotního nastavení modelů, kalibraci jejich parametrů, přes ověření spolehlivosti prostřednictvím nezávislého vzorku dat (validace), propojení se scénáři očekávaného vývoje klimatu v budoucnu až po hodnocení dopadů změny podmínek na významné polní plodiny a vybrané reprezentativní lokality v České republice.
Plný tet: Metodika_rustove_modely_2015 -  PDF
Plný text: content.csg - PDF
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Analysis of Spring Barley Actual Evapotranspiration
Pozníková, Gabriela ; Fischer, Milan ; Pohanková, Eva ; Žalud, Zdeněk ; Trnka, Miroslav
Evapotranspiration (ET) represents the main water-loss part of the water balance in agricultural landscape. The reliable quantification of the agricultural field ET is, however, still a challenge. To calculate ET, the Bowen ratio/energy balance (BREB) method was used in this study. It is based on measurements of the temperature and humidity gradients and radiation balance with the soil heat flux. Calculated ET was further used to quantify crop coefficient (Kc). Subsequently, we analysed the crop coefficient of spring barley during one growing season since 7th May 2013 to 30th July 2013. We used the data obtained above 1-ha spring barley field in Bystřice nad Pernštejnem, Czech Republic. In particular, we investigated how Kc correlates to climatic conditions as rainfall and soil humidity and how it reflects Plant Area Index (PAI) during the year during different parts of growing season. The cumulative ET of spring barley was 228.6 mm per investigated period. For reference evapotranspiration (ETo) two different approaches were used. Typically, a reference grass cover 0.12 m high standard for Europe. On the other hand, in the USA it is common to use also alfalfa (0.50 m high). ETo of grass was 296.3 mm and ETo of alfalfa was 351.4 mm. Maximum Plant Area Index occurred in June and its value was 4.1. Mean Kc in May was 1.17 for reference grass and 1.03 for alfalfa. Similarly in June, Kc was equal to 1.16 (grass) and 1.03 (alfalfa). Finally in July, for reference grass Kc was 0.55 and 0.48 for alfalfa. The decline at the end of the growing season was caused by dry weather and ripe stage of spring barley.
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