2957 research outputs found
Sort by
Seed Vigour Testing of Field Crops
No full textDo popředí zájmu se v rámci adaptačních opatření na vývoj klimatu v současnosti dostává šlechtění odrůd se zvýšenou tolerancí k abiotickým stresorům. Z pohledu tolerance k suchu je významnou růstovou fází již klíčení semen a následný vývoj klíčenců. Metody hodnocení klíčení jsou navrženy především do ideálních (laboratorních) podmínek, nicméně je přínosné znát reálné projevy semen v polních podmínkách, byť simulovaných. V tomto kontextu je testována schopnost semen vyklíčit za podmínek suboptimálních až stresových - tj. vitalita semen. Existuje předpoklad, že u genotypů s vitálnějšími semeny dojde, mimo jiné, ke zvýšení tolerance k suchu. Klíčenci z vitálnějších obilek uniknou snáze případnému suchu v počátečních fázích vegetace, vytvoří rychleji kořenový systém a budou tak tolerantnější ke stresovým podmínkám i v dalších fázích vegetace. Hodnocení parametrů vitality semen má potenciál realizace ve šlechtitelských programech. Předchozí výsledky potvrzují významný genetický základ vitality a jsou předpokladem pro využití této vlastnosti semen jako selekčního kritéria ve šlechtění. Standardně používané metody zjišťování vitality semen jsou zpravidla založeny na binárním přístupu - typicky v podobě: naklíčeno/nenaklíčeno. S rozvojem digitální optické techniky a digitální analýzy obrazu jsou vyvíjeny a úspěšně zaváděny metody exaktnějšího, detailnějšího a automatizovaného hodnocení vitality. Metody využívají pro hodnocení digitální skener a software pro digitální analýzu obrazu. Je tak umožněno precizní fenotypování odrůdových diferencí v rychlosti nárůstu biomasy kořenů nebo klíčku u značného počtu genotypů a jedinců. Získané fytometrické (morfometrické) charakteristiky mohou být konfrontovány s vybranými kvantitativními znaky produkce. Aktivity ve výzkumu a šlechtění na zlepšení vitality jsou prozatím velice limitované, vzhledem ke kvantitativní (polygenní) povaze dané vlastnosti a absenci vhodných metod, které jsou doporučeny mezinárodní autoritou typu ISTA (International Seed Testing Association).The seed quality is of increasing importance due to global climate change. In rapidly changing climatic conditions seed vigour become increasingly important seed characteristics. The most-used method of assessing the quality of seeds is testing of seed germination (realized under laboratory conditions). Laboratory testing of quality characters of seed is usually carried out in ideal conditions (optimal temperature and air humidity). This characteristic of seeds indicates the ability to germinate in ideal conditions (i.e. potential of seeds). Nevertheless, for detecting the properties of the seeds is also important to test under field conditions or in conditions close to the situation in the field. Seed vigour is the ability of seeds to germinate under stress conditions (drought, low temperatures, the lack of nutrients, saline soils, heavy metals contamination etc.). At this point comes to the fore vigour of seeds to germinate under stressful conditions. Vigorous seeds are able to withstand stressful environmental conditions at an early stage of growth. High seed vigour is a precondition for fast and homogenous field emergence and good malting quality in barley. Seed vigour tests are divided into: tests based on germination, physiological and biochemical tests and multifactor tests. Most of them are based on the principle of simulation stress conditions. In any case, the ability of repeatability and reproducibility of methods are important. Standard method that is used at this time for the seed vigour evaluation, is confined to simple physiological binary fact germinated/non-germinated. The seed vigour is a polygenic trait, with prospects of improvement by traditional breeding methods. Nevertheless, the seed vigour was due to lack of appropriate methods in breeding programs neglected in the history.Published Versio
Fomes fomentarius and F. inzengae-A Comparison of Their Decay Patterns on Beech Wood
Get PDFWood-decaying fungi are responsible for the degradation of wood and the alteration in its material properties. Fomes fomentarius (L.) Fr. is one of the most common white-rot fungi colonising coarse wood and standing trees. In recent years, according to their genetic, physiological, and morphological differences, Fomes inzengae (Ces. and De Not.) Lécuru was identified as an independent species. This article aimed to compare the impact of the degradation caused by both species on the anatomical, physical, and mechanical properties of beech wood. When comparing the degradation caused by different strains of both species, no statistically significant difference was found in mass loss (ML) or moisture content (MC). A relevant correlation between ML and MC was confirmed for both species. Variabilities in the density distribution of the degraded and intact bending samples were found to be statistically different. No relevant difference was observed in the modulus of rupture (MOR) between the two species after each exposure period. A strong linear relationship between the MOR and the dynamic modulus of elasticity was revealed for both species. Both species showed decay patterns typical for simultaneous white rot and soft rot. According to the presented results, the impact of both species on the investigated material properties of wood cannot be considered significantly different.O
Artificial Weathering Resistance and Biological Durability of Surface-Charred Beech Wood Combined with Linseed Oil Coating
Get PDFSpecimens of European beech wood (Fagus sylvatica L.) charred at 250 oC (4 min), 300 oC (2 min), and 350 oC (1 min) in combination with linseed oil coating were studied. The influence of the surface charring process and artificial weathering on surface discoloration, water absorption, and decay resistance were analyzed. Discoloration analysis showed a decrease in all parameters L*, a*, and b* due to the charring process. Coating with linseed oil caused a decrease in the L* parameter. An influence on parameters a* and b* was also demonstrated. As a result of the artificial weathering, the L* parameter increased in almost all groups. The group charred at 350 oC showed a decrease in L*. The parameters a* and b* were also affected. The effect of oil coating on discoloration during artificial weathering was negligible. The average water absorption of uncoated charred specimens decreased more than 50%. Damage due to artificial weathering disrupted the effect of the charring process. The effect of oil coating decreased depending on the length of partial immersion. Surface charring and oil impregnation slightly reduced the loss of beech wood mass caused by T. versicolor and P. placenta but could not fully protect the wood.O
Epiphytic microflora and mycotoxin content in meadows-Is plant biodiversity affecting fungal contamination?
Get PDFEcosystem services are an important aspect of grasslands utilization; however, they are often contradictory to their main purpose, which is a production of good quality and safe feed. In this study, we evaluated the difference between grass monocultures and species-rich mixtures in terms of epiphytic microflora and mycotoxin contamination levels. We hypothesized that higher species diversity would lead to higher microbial counts, which could lead to higher mycotoxin contamination risk. Differences in epiphytic fungal, yeast and total amount of microorganisms (CFU g -1) depending on the species diversity in the field has been evaluated by cultivation method. Concentration of deoxynivalenol (DON), zearalenone (ZEN) and aflatoxin B1 (AFB1) was measured by ELISA. Results are suggesting that higher total amount of microorganisms were found in monocultures, however, fungal and yeast counts were higher in species-rich mixtures. Higher species diversity of grasses was related to higher total microbial count (TMC) and yeast colonization of phyllosphere. Our results suggest higher risk of fungal phyllosphere colonization of species-rich mixtures with higher biodiversity and therefore higher risk of mycotoxin contamination of such feed.O
Temporal and spatial variability of phloem structure in Picea abies and Fagus sylvatica and its link to climate
Get PDFUsing a unique 8-year data set (2010-2017) of phloem data, we studied the effect of temperature and precipitation on the phloem anatomy (conduit area, widths of ring, early and late phloem) and xylem-ring width in two coexisting temperate tree species, Picea abies and Fagus sylvatica, from three contrasting European temperate forest sites. Histometric analyses were performed on microcores taken from tree stems in autumn. We found high interannual variability and sensitivity of phloem anatomy and xylem-ring widths to precipitation and temperature; however, the responses were species- and site-specific. The contrasting response of xylem and phloem-ring widths of the same tree species to weather conditions was found at the two Slovenian sites generally well supplied with precipitation, while at the driest Czech site, the influence of weather factors on xylem and phloem ring widths was synchronised. Since widths of mean annual xylem and phloem increments were narrowest at the Czech site, this site is suggested to be most restrictive for the radial growth of both species. By influencing the seasonal patterns of xylem and phloem development, water availability appears to be the most important determinant of tissue- and species-specific responses to local weather conditions.Postprin
Examining the spatial spillover of gambling regulation in the Czech Republic
Get PDFThe responsibility of spatial regulation of gambling in the Czech Republic is placed on municipalities, the smallest self-governing units in the country. This creates a possibility that the effectiveness of regulation may be reduced by spatial spillover to the neighboring municipality. The aim of this paper is to evaluate to what extent the local reduction of gambling is effective in the overall reduction of gambling in the area under the conditions of fragmented regulation and mobility of gamblers. OLS regression was used to identify the spatial spillover effect. The decline in tax revenue on gambling machines in a district capital by one percentage point is associated with the rise of the same revenue in surrounding municipalities that are reachable in 10 min by 0.45 of a percentage point. Spatial spillover in more distant municipalities is close to zero. The results remain stable when control variables are employed. The results suggest that fragmented regulation is easy to overcome and better cooperation among municipalities or regulation on higher administrative level may be more effective.OA-hybri
Synergy or disparity? Czech experts' insights on migration and development policies
Get PDFThis article discusses the promotion of policy coherence of migration and development policies that have figured high on the agenda of international organizations and the European Union but have been hardly explored in the context of Central and Eastern Europe. Based on in-depth interviews with 40 Czech experts on migration and development, we identified three key contradictions: (i) The increasing prominence of a security perspective on both migration and development policies and the lack of coherence between these policies in practice; (ii) The tension between the national and transnational perspectives guiding migration policymaking and development policies; and (iii) The lack of reflection on crucial issues, such as remittances and brain drain, in the dominant paradigm of labour migration. We argue that the findings on (in)coherence between Czech migration and development policies help us understand policy responses of Central and Eastern European governments since the 2015 'migration crisis'.OA-hybri
Comparison of cell death rate in various chicken lymphocytes populations in a response to three temperature treatments
Get PDFThe goal of the experiment was to evaluate susceptibility of lymphocytes populations derived from bursa of Fabricius, spleen, thymus, and blood to temperature treatments in vitro. Temperatures used in study was 37 & DEG;C (thermoneutral), 41 & DEG;C (mild heat stress) and 45 & DEG;C (severe heat stress). Cells were incubated for 8 hours and after 3 and 8 hours were measured numbers of apoptotic, necrotic and CellROX positive cells by flow cytometry. Representation of live lymphocyte phenotypes (CD3, CD4, CD8, BU1) in cell populations were also measured. At all temperature treatments, thymus lymphocytes population had the lowest (p < 0.05) percentage of apoptotic cells. On the other hand, significantly highest numbers (p < 0.05) of apoptotic cells were found in bursal lymphocytes after 8 hours of incubation. Differences in numbers of necrotic cells were more pronounced at 45 & DEG;C, where after 3 and 8 hours of incubation were significantly highest numbers (p < 0.05) of necrotic cells in spleen. Increasing temperature induce production of reactive oxygen species (ROS) in cells and highest proportion (p < 0.05) of ROS-positive cells were found in bursal and spleen cell population after 8 hours of incubation. Transmission electron microscopy showed loss of mitochondrial matrix and disrupted mitochondrial membrane in mitochondria of lymphocytes at 45 & DEG;C as initial damage caused by ROS. From individual cell phenotypes, there were significantly decreased (p < 0.05) B lymphocytes in bursa of Fabricius, CD4+ and CD8+ lymphocytes in thymus and whole T lymphocytes population in spleen at 45 & DEG;C. Various susceptibility to temperature can be predictive factor of worse function in some organs in stress conditions where body temperature increase.O
A review of the performance of fibre-reinforced composite laminates with carbon nanotubes
Get PDFImpact loads lead to the failure of structures and significantly diminish their operational lifespan. The necessity to enhance impact performance has shown gradual progress, resulting in utilising nano-fillers as an additional reinforcement within the matrix. Despite the significant number of studies that have been done on this unique hybrid material, there have only been a few reviews published that discuss the effect of production processes on mechanical properties and performance in these hybrid composites under projectile impact. There have been conflicting results obtained in experimental results from the literature. The disparity is related to the variation in dispersion, bonding states, and inconsistent fabrication processes. This work defines the pros and cons of carbon nanotube (CNT)-based composites along with a systematic representation of the development of CNT-reinforced composites under projectile impact using experimental, analytical, and numerical techniques. The potential of CNT reinforcement on fibre-reinforced polymers (FRPs) and its effect on mechanical properties have been discussed. Furthermore, different impact test setups are explored to determine the effective method to determine the impact performance of CNT-reinforced laminates. Moreover, the impact of surface treatment is discussed using different non-destructive methods, and the influence of CNT reinforcement is determined. In addition, mechanical and impact response with varying configurations of fibres is gathered from the available literature, and optimal design based on the required application is suggested. Also, analytical methods developed to determine the impact response of laminates are discussed to determine the parameters dominating the impact response of the laminate. This review will help researchers find the right combination of FRP materials for a given application.O
Value Creation with Digital Twins: Application-Oriented Conceptual Framework and Case Study
Get PDFThe internet of things, digital twins of smart connected products, and thereby enabled smart services are topics of great interest and have been gaining traction for many years. However, many questions concerning the application-oriented usage of digital twins still need to be scrutinized. Therefore, this paper examines the question of an application-oriented framework for value creation with digital twins using design science research approaches. A conceptual reference framework is presented based on earlier research and iteratively developed within workshops with three companies. The framework incorporates primary dimensions of external and internal value creation and data resources. Further, it discusses the product life cycle, the real-world counterpart, value creation in the ecosystem, and the generational aspect of the digital twins. Furthermore, applying the framework to a use case with an industrial research partner helps to show the contributions to the industrial sector. The framework provides utility to practitioners as a means of creating a common sense in interdisciplinary teams, communicating digital twin projects to internal and external stakeholders, and as a toolbox for specific challenges concerning digital twins. In addition, the framework distinguishes itself from existing approaches by including the service ecosystem and its actors while considering the principles of product life cycle management. Therefore, using the framework in other use cases will test the approach on different industries and products. Furthermore, there is a need to develop approaches for implementing and developing an existing case.O