92 research outputs found
Agronomic Characteristics of Novi Sad Winter Vetch Cultivars
Genus Vicia. contains important annual food and forage species such as field bean, V. faba., narbon vetch, V. narbonensis, and common vetch, V. sativa (Maxted, 1995), while Hungarian V. pannonica Crantz and hairy vetch V. villosa also play an important role in the Balkans. Winter vetches are excellent forage catch crops useful for sustainable agriculture and organic farming (Ċupina et al., 2004). Our study was aimed at determining the agronomic characteristics of the winter vetch cultivars developed in Novi Sad, assessing thus their ability for successful growing in the prevailing conditions of Serbia and Montenegro
Hemijski sastav lišća i stabljika divergentnih sorti lucerke
Alfalfa is a perennial crop that provides a higher yield of proteins per unit area than any field crop, which makes it highly desirable for the production of hay and feed for domestic animals (especially ruminants). The objective of this study was to determine the dry matter chemical composition in the whole plant, leaves and stems of five divergent alfalfa cultivars. Variations were found in the contents of proteins, hemicellulose, NDF, ADF, ADL, cellulose, and minerals depending on genotype and plant part. Significant differences existed between the cultivars in quality parameters, indicating that breeding for high alfalfa quality is justifiable.Lucerka je višegodišnja vrsta koja daje veći prinos proteina po jedinici površine od bilo koje ratarske kulture, pa je zbog toga veoma poželjna za proizvodnju sena i u ishrani domaćih životinja (posebno preživara). Cilj rada je bio da se odredi hemijski sastav suve materije lucerke kod pet divergentenih sorti lucerke u celoj biljci kao i u listu i stabljikama. Lucerka varira u sadržaju proteina, celuloze, hemiceluloze, NDF, ADF, ADL, i mineralnih materija u zavisnosti od genotipa i biljnog dela. Postoje značajne razlike u komponentama hranljive vrednosti lucerke između sorti što ukazuje da oplemenjivanje na veći kvalitet lucerke ima smisla
Structure and Dynamics of the Sun's Open Magnetic Field
The solar magnetic field is the primary agent that drives solar activity and
couples the Sun to the Heliosphere. Although the details of this coupling
depend on the quantitative properties of the field, many important aspects of
the corona - solar wind connection can be understood by considering only the
general topological properties of those regions on the Sun where the field
extends from the photosphere out to interplanetary space, the so-called open
field regions that are usually observed as coronal holes. From the simple
assumptions that underlie the standard quasi-steady corona-wind theoretical
models, and that are likely to hold for the Sun, as well, we derive two
conjectures on the possible structure and dynamics of coronal holes: (1)
Coronal holes are unique in that every unipolar region on the photosphere can
contain at most one coronal hole. (2) Coronal holes of nested polarity regions
must themselves be nested. Magnetic reconnection plays the central role in
enforcing these constraints on the field topology. From these conjectures we
derive additional properties for the topology of open field regions, and
propose several observational predictions for both the slowly varying and
transient corona/solar wind.Comment: 26 pages, 6 figure
3D Coronal Density Reconstruction and Retrieving the Magnetic Field Structure during Solar Minimum
Measurement of the coronal magnetic field is a crucial ingredient in
understanding the nature of solar coronal phenomena at all scales. We employed
STEREO/COR1 data obtained during a deep minimum of solar activity in February
2008 (Carrington rotation CR 2066) to retrieve and analyze the
three-dimensional (3D) coronal electron density in the range of heights from
1.5 to 4 Rsun using a tomography method. With this, we qualitatively deduced
structures of the coronal magnetic field. The 3D electron density analysis is
complemented by the 3D STEREO/EUVI emissivity in the 195 A band obtained by
tomography for the same CR. A global 3D MHD model of the solar corona was used
to relate the reconstructed 3D density and emissivity to open/closed magnetic
field structures. We show that the density maximum locations can serve as an
indicator of current sheet position, while the locations of the density
gradient maximum can be a reliable indicator of coronal hole boundaries. We
find that the magnetic field configuration during CR 2066 has a tendency to
become radially open at heliocentric distances greater than 2.5 Rsun. We also
find that the potential field model with a fixed source surface (PFSS) is
inconsistent with the boundaries between the regions with open and closed
magnetic field structures. This indicates that the assumption of the potential
nature of the coronal global magnetic field is not satisfied even during the
deep solar minimum. Results of our 3D density reconstruction will help to
constrain solar coronal field models and test the accuracy of the magnetic
field approximations for coronal modeling.Comment: Published in "Solar Physics
Three‐dimensional MHD simulation of a flux rope driven CME
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94917/1/jgra16823.pd
Initiation and propagation of coronal mass ejections
This paper reviews recent progress in the research on the initiation and
propagation of CMEs. In the initiation part, several trigger mechanisms are
discussed; In the propagation part, the observations and modelings of EIT
waves/dimmings, as the EUV counterparts of CMEs, are described.Comment: 8 pages, 1 figure, an invited review, to appear in J. Astrophys.
Astro
Determination of Population Structure of Wheat Core Collection for Association Mapping
The microsatellites, as one of the most robust markers for identification of wheat varieties, were used for assessment of genetic diversity and population structure to promote effective use of genetic resources. In this study, the set of 284 wheat varieties were genotyped using 30 microsatellite markers. The chosen SSR markers were located among almost all linkage groups and covered all three genomes. The genotypes used originate from 24 different breeding centers worldwide and are included in an extensive core collection of the Institute of Field and Vegetable Crops in Novi Sad, Serbia. The total number of detected alleles was 349 at all analyzed loci. The average number of detected allelic variant per locus was 11.5. The mean value of polymorphic information content was 0.68. According to the probability of data obtained by program Structure, the results have shown presence of 6 subpopulations within the studied set of genotypes. The population structure positively correlated to some extent with geographic origin. The available pedigree data were included for additional explanation of population structure. The results of this study should provide valuable information for future association studies using the diverse wheat breeding material
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Assessing the quality of models of the ambient solar wind
In this paper we present an assessment of the status of models of the global Solar Wind in the inner heliosphere. We limit our discussion to the class of models designed to provide solar wind forecasts, excluding those designed for the purpose of testing physical processes in idealized configurations. In addition, we limit our discussion to modeling of the ‘ambient’ wind in the absence of coronal mass ejections. In this assessment we cover use of the models both in forecast mode and as tools for scientific research. We present a brief history of the development of these models, discussing the range of physical approximations in use. We discuss the limitations of the data inputs available to these models and its impact on their quality. We also discuss current model development trends
Global destabilization due to localized reconnection: A mechanism for coronal mass ejections
The Origin, Early Evolution and Predictability of Solar Eruptions
Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal mass ejections and failed eruptions; all thought to be due to a release of energy stored in the coronal magnetic field during its drastic reconfiguration. This review discusses the observations and physical mechanisms behind this eruptive activity, with a view to making an assessment of the current capability of forecasting these events for space weather risk and impact mitigation. Whilst a wealth of observations exist, and detailed models have been developed, there still exists a need to draw these approaches together. In particular more realistic models are encouraged in order to asses the full range of complexity of the solar atmosphere and the criteria for which an eruption is formed. From the observational side, a more detailed understanding of the role of photospheric flows and reconnection is needed in order to identify the evolutionary path that ultimately means a magnetic structure will erupt
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