National Repository of Grey Literature 23 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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.
Interactive effects of elevated CO2 concentration, nitrogen nutrition and UV-exclusion on yield, aboveground biomass and root development in winter wheat and spring barley
Rattanapichai, W. ; Klem, Karel
Within the manipulation experiment in open top chambers (Domaninek near Bystrice nad Pernstejnem) that allow simulation of elevated concentration of CO2 ([CO2]) (expected by the end of this century700 mu mol mol(-1)) and exclusion of solar UV radiation, the interactive effects of these environmental drivers together with nitrogen application were studied. Aboveground biomass at the time of harvest, grain yield and root area were studied in winter wheat (variety Bohemia) and spring barley (variety Bojos). From three replications of each treatment were the roots of four plants dug out from the soil and gently washed. Photos of roots taken using the digital camera were analysed by image processing software Image J (plugin SmartRoot). The result showed that the elevation of [CO2] increased the above ground biomass and grain yield. High level of nitrogen increased the stimulatory effect of [CO2] on the above-ground biomass and grain yield. Also UV exclusion stimulated the effect of the evaluated [CO2] on above-ground biomass and grain yield. UV exclusion resulted in higher root area than the treatment of non-exclusion of UV.
Methods of detection of fungal diseases applicable in plant phenotyping and remote sensing
Klem, Karel ; Veselá, Barbora ; Holub, Petr ; Urban, Otmar ; Mezera, J.
This methodology summarises findings from a comparison of three perspective methods of fungal disease detection applicable for remote sensing and plant phenotyping of fungal disease resistance. These methods are spectral reflectance, infrared thermal imaging, and blue-green fluorescence imaging. On the example of winter wheat infection with powdery mildew, stripe rust and brown rust the strengths and weaknesses of individual methods were demonstrated. From these results it is evident that all three methods are potentially applicable for non-destructive fungal disease detection, but their practical use may vary. Testing of spectral reflectance indices for the detection of fungal diseases showed particularly the high detection reliability of the red-edge and green band based spectral vegetation indices. Infrared thermal imaging has shown high detection accuracy for powdery mildew and brown rust, but lower for stripe rust. Blue-green fluorescence and thermal imaging seems to be also a very promising tools for evaluating the intensity and spatial distribution of infection on a leaf level.
Integrated weed management in cereals
Smutný, V. ; Winkler, J. ; Klem, Karel
Certified methodology summarized knowledge about the impact of different non-direct (preventive) agronomic measures (crop rotations, soil tillage, fertilization using organic fertilizers and straw management) on weeds (weed seedbank and actual weed infestation), from qualitative (weed specie composition) and quantitative (intensity occurrence) point of view). There is also particular focus on rationalization of chemical methods of weed management (herbicide application). Principles of decision-making rules based on establishment of economic thresholds, optimal timing of application and optimization of herbicide doses. There is a potential for decrease of applied herbicides in cereals using of this approach, which brings not only considerable economic savings, but also reduction of negative environmental effect caused by herbicide use.\n\n
Quantitative analysis of biophysical parameters of crops using multispectral data Copernicus
Mišurec, J. ; Lukeš, Petr ; Tomíček, J. ; Klem, Karel ; Jakešová, L.
The development of a methodology for retrieval of biophysical parameters using multispectral satellite data Sentinel-2 has been optimized for the most frequently grown crops in the Czech Republic: winter wheat, spring barley, oilseed rape, lucerne, maize and sugar beet. The target crop parameters were chlorophyll and water content in leaves and leaf area index (LAI). The method of calculating biophysical parameters was based on the use of the ProSAIL radiation transfer model, where the model simulates canopy status for various combinations of biophysical parameters in inverse mode. A combination of biophysical parameters, showing the best match for the reflectance values observed by the Sentinel-2 satellite system is searched. Developed products will find use in farms, for example in planning the management of agricultural land.
Predicting light use efficiency using optical vegetation indices at various time scales and environmental conditions
Kováč, Daniel ; Ač, Alexander ; Veselovská, Petra ; Dreveňáková, Petra ; Rapantová, Barbora ; Klem, Karel
This study presents data points acquired during 2 years of measuring optical properties and gas-exchange\ncharacteristics of European beech (Fagus sylvatica) and Norway spruce (Picea abies) tree species in controlled\nenvironments. The observed statistical relationships between 105 pairs of selected optical parameters\n(i.e. photochemical reflectance index [PRI], ΔPRI, and normalized difference between wavebands R690\nand R630 [where R is a reflectance at a subscripted wavelength]) and light use efficiency (LUE) were considered\nat assumed different canopy leaf area index, changing pigments stoichiometrics, and daily changing\ndynamics of environmental conditions. Our measurements suggested that consistency of the LUE estimation\nusing PRI may be disrupted by acclimation responses of plants that reduce energetic carriers for\nuse in photosynthetic CO2 uptake and the xanthophyll cycle. Also, a changing chlorophylls-to-carotenoids\nratio tends to interrupt the PRI–LUE relationship. ΔPRI showed sensitivity to leaf area index of the measured\ntrees that complicated leaf-level estimation of LUE. The most consistent assessment of LUE was\nachieved using the chlorophyll fluorescence detecting ratio (R690 – R630)/(R690 + R630).
Influence of the chlorophylls-to-carotenoids ratio on light use efficiency estimation by optical parameters
Ač, Alexander ; Kováč, Daniel ; Veselovská, Petra ; Večeřová, Kristýna ; Klem, Karel
The influence is examined of changing leaf photosynthetic pigments concentrations on sensitivity of the\nphotochemical reflectance index (PRI) and ΔPRI optical parameters in relation to light use efficiency\n(LUE). Photosynthetic and leaf chlorophylls-to-carotenoids (Chl/Car) ratio changes during the growth of\nEuropean Beech (Fagus sylvatica) and Norway spruce (Picea abies) saplings were induced by altering the\nliving environment inside growth chambers. Point reflectance measurements of each individual tree were\nrecording changes in optical properties while measurements were being taken simultaneously of altering\nphotosynthesis. Based on the evaluation of 45 pairs of measurements conducted on six individual saplings,\nthe observed variability in the strength of the PRI and ΔPRI versus LUE relationships was compared to the\nresulting leaf Chl/Car ratio of each tree. Data were used to explain the influence of changing pigments on\nthe sensitivity of each individual optical parameter with regards to the LUE estimation.
Effect of elevated CO2 on morphological and photosynthetic parameters in two understory grass species in Beskydy Mountains
Holub, Petr ; Klem, Karel ; Urban, Otmar
We transplanted two grass species, Calamagrostis arundinacea and Luzula sylvatica, to the understory of\na 10-year-old experimental mixed forest exposed to ambient (385 μmol CO2 mol–1, AC) and elevated (700\nμmol CO2 mol–1, EC) atmospheric CO2 concentration using a glass dome facility. Effects of EC on plant\nmorphology and photosynthesis were examined after three years of treatment. We tested the hypotheses\nthat shade-tolerant species can profit from EC even at low light conditions and that relatively low accumulation\nof assimilates at such light conditions will not cause CO2-induced down-regulation of photosynthesis.\nWe expected that EC can substitute insufficient light intensities under the tree canopy and lead to both\nhigher biomass production and survival of plants in deep forest understories. The typical shade-tolerant\nspecies L. sylvatica exhibited positive acclimation under EC allowing higher light use efficiency under subsaturating\nlight intensities as compared to plants grown under AC. In contrast, C. arundinacea showed\nhigher stimulation of growth and photosynthetic rates by EC mainly under saturating light intensities at\nthe beginning of the growing season, when the forest leaf area is not fully developed and the open canopy\nallows a greater proportion of incident light to reach the understory. Our data indicate that growth and\nphysiological responses of EC plants in forest understories are species specific, differ from responses of\nsun-exposed plants, and depend on degree of shading.
Interactive effect of UV radiation and CO2 treatment on extractable volatile organic compounds from European beech leaves
Večeřová, Kristýna ; Pernicová, N. ; Klem, Karel ; Urban, Otmar
The main objective of this experiment was to investigate the combined effect of different UV treatments\nand elevated CO2 concentration on monoterpene and methyl salicylate (MES) content in leaves of\nEuropean beech during the growing season. Plants were grown under ambient (AC, 400 μmol mol–1) and\nelevated (EC, 700 μmol mol–1) CO2 concentrations and three UV radiation treatments (ambient – UVamb,\nexcluded – UV-, and enhanced – UV+). Leaves collected from July to September were extracted in cold\nheptane to determine volatile organic compounds content using gas chromatography. Our results show\nthat AC plants had higher total content of extractable monoterpenes and MES than did EC plants over\nthe whole growing season and irrespective of UV treatment. Limonene, 2-bornene, and ester MES were\nthe most abundant volatile compounds in beech leaves. The highest contents of 2-bornene and MES were\nfound under the UV- treatment and AC. Contents of α-pinene, β-pinene, and carene decreased during the\ngrowing season while the content of limonene increased.
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.

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