National Repository of Grey Literature 32 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Short-term application of elevated temperature and drought influences the isotopic composition of winter wheat grains
Pernicová, Natálie ; Urban, Otmar ; Čáslavský, Josef ; Klem, Karel ; Trnka, Miroslav
The study aimed to determine the differences in carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in grains of three winter wheat varieties grown under optimal and stress conditions. We found that the wheat variety has a significant effect on both δ13C and δ15N isotope ratios. Short-term (nine days) exposure to drought and high temperature during the heading or stem extension development phase significantly enhanced δ13C values, but only high temperature affected δ15N values. Enhanced δ15N values support the assumption that global warming causes a higher representation of the 15N isotope in plants. Moreover, significant interactive effects of temperature and water availability on the values of both isotopes were found implying that C and N metabolisms have been altered under the investigated stress conditions. We conclude that δ13C and δ15N isotope ratios of cereal grains are sensitive indicators of stress conditions, even short-term ones
Estimation of winter wheat yield using machine learning from airborne hyperspectral data
Švik, Marian ; Pikl, Miroslav ; Janoutová, Růžena ; Veselá, Barbora ; Slezák, Lukáš ; Klem, Karel ; Homolová, Lucie
Methods based on optical remote sensing allow nowadays to assess crop conditions over larger areas. The assessment of crop conditions and potential estimation of crop yields in the early growth\nstages can help farmers to better target their management practice such as application of fertilizers. In this study we analysed airborne hyperspectral images acquired several times during the growing season over two experimental sites in the Czech Republic (Ivanovice and Lukavec). The field experiments on winter wheat included 12 levels of fertilisation (combination of organic and mineral fertilisers). Such an experiment design and the possibility of combining the data from two sites together increased the variability in our wheat yield dataset, which varied between 2.8 and 10.0 t/ha. Further, we used a machine learning method – namely gaussian process regression from the ARTMO toolbox to train two variants of models: a) combining the spectral data from both sites and from the multiple acquisition days and b) combining the spectral data from both sites for individual acquisition days.The results showed that it was feasible to predict wheat yield already at the beginning of April with R2 > 0.85. This promising result, however, requires more thorough validation and therefore we plan to include more data from other sites in the next steps.
Effect of elevated CO2 concentration and nitrogen nutrition on mais response to short-term high temperature and drought stress
Simor, J. ; Klem, Karel
Within an experiment conducted in open top chambers in which two mais genotypes differing in stay-green trait were cultivated under elevated atmospheric CO2 concentration (EC) in comparison\nwith ambient CO2 concentration (AC), and in two contrast levels of nitrogen nutrition, the effect of acclimation to these factors on photosynthetic performance and water use efficiency, and subsequent response to short-term high temperature and drought stress was studied. Although EC improved water use efficiency, this effect did not alleviate the response to drought stress, and under some combinations of factors even led to a decrease in CO2 assimilation rate under drought stress. Differences in the stay- green trait between genotypes did not have a major effect on the response to high temperature and drought stress. Differences between genotypes were manifested mainly in the interaction with nitrogen nutrition, while in the Korynt genotype, non fertilised variants showed a lower response of CO2 assimilation rate to drought. Slight alleviating effect of higher nitrogen dose was found under EC conditions, while no nitrogen fertilisation rather increased drought resilience under AC conditions.
Interactive effects of adaptation technology, based on no-till sowing into the mulch of cover crop residues, and nitrogen nutrition on photosynthetic performance of maize under drought stress
Opoku, Emmanuel ; Holub, Petr ; Findurová, Hana ; Veselá, Barbora ; Klem, Karel
The aim of this study was to evaluate the interactive effect of adaptation technology based on no-till sowing into cover crop mulch and nitrogen nutrition on photosynthetic performance of maize under short term drought stress induced by rain-out shelters. The experiment was established in two locations in the same climatic condition but differing in soil fertility. The negative effect of drought on CO2 assimilation rate was modulated by nitrogen nutrition. However, while nitrogen nutrition led to alleviating effect at the location with higher fertility, the opposite effect was found at the site with lower fertility. Adaptation technology had only a minor impact on photosynthetic response to drought, but it generally increased CO2 assimilation rate at the site with higher soil fertility and decreased at the site with lower soil fertility. We can conclude that adaptation technology, despite of assumptions, did not significantly change the resilience of maize to drought, and probably longer use of such technology is required to improve soil water retention and thus also balanced supply of water to plants. \nAt the same time, we did not find a negative impact of adaptation technology on photosynthesis which can be related to cooler soil during maize emergence and slower mineralization, although the use of adaptation technology seems to be more effective in soils with higher fertility.
Variation of glomalin content in the Czech soils and the relationships to the chemical soil characteristics and climatic regions
Polách, Vojtěch ; Patra, Sneha ; Klem, Karel
Glomalin is being investigated as a substance that improves soil quality, the resistance of soil aggregates and play a role in carbon sequestration. This study is the first nationwide survey of the glomalin content in the soil. Soil samples were collected from 181 locations in the Czech Republic to describe the variability of glomalin content in the soils of the Czech Republic and its dependence on soil chemical properties and climatic area. Sodium citrate buffer was used to extract easily extractable glomalin (EEG), and the glomalin concentration was determined spectrophotometrically. The soil glomalin content correlates most with the ratio of humic and fulvic acids. Moreover, the interrelation between glomalin content and climatic regions was also observed. The content of glomalin decreases from the warmest regions to the coldest. We also compared the glomalin content among different soil types groups and found out that the lowest glomalin content was found in Entic Podzols and Gleysols. On the contrary, the highest glomalin content was found in Vertisols, Phaeozems and Luvisols.
Atmospheric CO2 concentration, light intensity and nitrogen nutrition affect spring barley response to drought and heat stress
Findurová, Hana ; Veselá, Barbora ; Opoku, Emmanuel ; Klem, Karel
The aim of this study was to compare physiological responses of two spring barley varieties,\ndiffering in their oxidative stress tolerance, to drought and heat stress after pre-treatment under different\nirradiation regimes, CO2 concentrations, and nitrogen fertilisation levels. High light intensity, elevated\nCO2, and additional UV radiation increased flavonoid accumulation. Moreover, more flavonoids were\ninduced in oxidative stress-sensitive variety Barke. Combined drought and heat stress caused a large\ndecline in CO2 assimilation, whereas heat stress alone caused only minor changes. Under combined\nstress, plants grown under low light intensity and no UV irradiation performed the best despite their\nhigher initial water use efficiency and lower flavonoids content.
Quo Vaditis Agriculture, Forestry and Society under Global Change? From understanding past and present Earth´s processes to adaptations for the future
Šprtová, Miroslava ; Bartošová, Lenka ; Acosta, Manuel ; Klem, Karel ; Leventon, Julia ; Červený, Jan
International conference „Quo vaditis agriculture, forestry and society under Global Change? From understanding past and present Earth’s processes to adaptations for the future“, whose scientific sponsor is the European Center of Excellence CzechGlobe, should prove that science has an irreplaceable role in addressing mitigation and adaptation to climate change, in meeting international commitments to climate change and tasks of the EU Strategy on adaptation to climate change.
Yield formation parameters of winter wheat under two CO2 levels in water sufficient and depleted environment
Hlaváčová, Marcela ; Klem, Karel ; Veselá, Barbora ; Findurová, Hana ; Hlavinka, Petr ; Smutná, P. ; Horáková, V. ; Škarpa, P. ; Trnka, Miroslav
Agricultural production faces with ongoing climate that in Europe takes form of changing seasonal precipitation pattern with more frequent drought spells. These changes come on top of rising air temperature and did and will affect productivity as well as onset and duration of key developmental stages for yield formation of major staple crops such as wheat. In order to ensure stable agricultural production and satisfy demand of the increasing humanpopulation, it is crucial to know responses of major field crops to these abiotic stress factors to assess suitability of genotypes to specific environmental conditions. The aim of this study was to evaluate final yield formation parameters of five winter wheat genotypes cultivated in pots and exposed to two different levels of CO2 concentrations (400 ppm as ambient and 700 ppm as elevated CO2 concentrations) and two water treatments (well- watered control and drought-stressed plants). Theexperimental treatments were set up in growth chambers from the end of heading stage (BBCH 59)to the beginning of ripening stage (BBCH 71) to simulate the conditions under future climate. The results showed that elevated CO2 concentration led to: (1) mitigation of reduction in final yield formation parameters of drought-stressed plants compared to those of control, (2) enhanced results of drought-stressed treatments compared to those of drought-stressed treatments exposed to the ambient CO2 concentration. Pannonia NS was found out as the less responsive genotype to the exposition of CO2 concentration (no statistically significant differences among ambient and elevated CO2 concentrations in all yield formation parameters were identified). On contrary, harvest index of genotype Bohemia was identified as the most sensitive parameter in response to drought stress as well as to the atmospheric CO2 concentration.
Interactive effects of elevated CO2 concentration, drought and nitrogen nutrition on malting quality of spring barley
Simor, J. ; Klem, Karel ; Psota, V.
Elevated CO2 concentration [EC] generally leads to increased rates of photosynthesis, increased formation of assimilates and finally to storing them in the grain. Increased storage of starch in the grain, however, leads to an unbalanced proportion to the proteins, and their relative content decreases. This is particularly apparent in the conditions of nitrogen deficiency. The interactive effects of EC, nitrogen nutrition and reduced water availability are, however, not yet sufficiently understood. Within the manipulation experiment in open top chambers (Domaninek near Bystrice nad Pernstejnem) that allow simulation of EC (expected by the end of this century 700 ppm) and drought, the effect of these interactions on protein content, and other quality parameters of spring barley grain was studied. EC reduced grain protein content, increased extract, Kolbach index and also summary Malting quality index. Such effect was more pronounced under higher nitrogen dose, which generally worsened malting quality parameters. Reduced water availability slightly enhanced all malting quality parameters and also showed slight synergistic effect to EC. No clear interactive effects on malting quality were found for nitrogen nutrition and water availability.
Effect of exogenous application of growth regulators on the physiological parameters and the yield of winter wheat under drought stress
Barányiová, I. ; Klem, Karel ; Křen, J.
The field trial aimed to evaluate the effect of different growth regulators in winter wheat under growth stress was conducted in 2013/2014. Within this experiment following growth regulators and fungicide with growth regulation effect were used: Retacel extra R68 (chlormequat chloride 720 g/l), Moddus (trinexapac-ethyl 250 g/l), Cerone (ethephon 480 g/l), Amistar (strobulirin 250 g/l). These growth regulators were applied at growth stages between BBCH 31 and BBCH 59. The aim of the experiment was to determine the impact of these regulators on the growth, development and yield of winter wheat when simulating the drought stress using experimental rain-out shelters. The attention was paid to assess the effect of exogenous application of growth regulators on the physiology and the yield of selected varieties of winter wheat under drought stress. From our preliminary results it can be concluded that almost all growth regulators increase the rate of CO2 assimilation and the stomatal conductance. Definitely positive effect on water use efficiency was found in fungicide treatment with growth regulation effect azoxystrobin. Under drought stress the decrease of chlorophyll content in leaves was found. Growth regulators CCC and trinexapac mitigate the decline of chlorophyll content caused by drought in the upper leaves but rather increased the impact in older (lower) leaves. Fungicide azoxystrobin alleviates the decrease of chlorophyll caused by drought in all leaves. The results show that all regulators increased yield, which demonstrate a positive effect under dry conditions because the vegetation season was very dry and lodging did not occur. Furthermore, the most pronounced mitigation of drought stress was found for strobilurin and partly also trinexapac. Results of field experiments can contribute to mitigating the impact of drought on yield formation and quality of winter wheat production in the realization of biological potential of wheat genotypes.

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