1,721,027 research outputs found
Race spectra of Leptosphaeria maculans, the causal agent of blackleg disease of oilseed rape, in different geographic regions in northern Germany
No full textThe fungal pathogen Leptosphaeria maculans (LM), causing blackleg in oilseed rape (OSR), develops gene-for-gene interactions with OSR cultivars. Thus, virulent races can cause severe OSR yield losses in genotypes that depend only on the major resistance genes. LM race spectra were determined using 644 isolates collected from four OSR growing areas in northern Germany in autumn 2011 and 2012. Avirulence alleles (AvrLm) and race spectra of the isolates was identified with OSR cultivars harbouring the major genes Rlm1, Rlm2, Rlm3, Rlm4, Rlm7, and Rlm9. Thirteen LM races were determined, whereby 85 % of the collected isolates belonged to race AvrLm(5)-(6)-7-(8) (virulent to Rlm1-4 and Rlm9) and 10 % belonged to race AvrLm1-(5)-(6)-7-(8) (virulent to Rlm2-4 and Rlm9). Only six of 644 isolates (0.9 %) showed virulence to Rlm7. Using tester isolates that identify Rlm7, we showed that Rlm7 was absent in the most sown cultivars in northern Germany, explaining the low frequency of isolates being virulent to Rlm7. However, blackleg disease incidence (DI) increased significantly in the cultivar Exocet (harbouring Rlm7) between 2011/12 and 2012/13, whereas DI was the same in a susceptible control cultivar across all sampled regions and years. Our results show that Rlm7 is the only known major resistance gene in German OSR cultivars that is still effective against LM, but increasing deployment in commercial cultivars may foster resistance breakdown in the future
Crop rotation effects on incidence and diversity of Fusarium species colonizing stem bases and grains of winter wheat
No full textFusarium head blight (FHB) and Fusarium crown and foot rot (FCR) are the most important diseases caused by Fusarium species in wheat. Although the range of Fusarium species colonizing wheat ears and stem bases is known, the impact of various crop rotations on the diversity and incidence of such species has not been investigated thoroughly. We therefore analyzed the occurrence of Fusarium species on stem bases and grains of wheat grown in four different long-term crop rotations that included winter wheat, maize, sugar beet and oil radish as pre-crops. The results demonstrate that, regardless of the crop rotation, the range of Fusarium species that colonized stem bases and grains of wheat was consistent. Stem bases were predominantly infected by F. culmorum, F. equiseti and F. tricinctum, while F. graminearum, F. poae and F. tricinctum were mainly found on grains. However, the colonization frequencies of Fusarium spp. both in stem bases and grains were differentially affected by crop rotations. Highest infestation in grains was found when wheat was grown after maize, dominated by F. graminearum, while wheat grown after sugar beet led to highest colonization frequencies of F. culmorum in stem bases. Among all identified Fusarium species, F. culmorum was the dominant causal agent of FCR. The results of this study indicate that sugar beet and maize as pre-crops of wheat may increase the risk of FCR and FHB, respectively, to a much greater extent than wheat grown after wheat, which did not have such critical effects on the incidence of the two diseases.Ministry of Science and Culture of Lower Saxony, German
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Cropping systems with maize and oilseed rape for energy production may reduce the risk of stem base diseases in wheat
No full textCropping systems with crops cultivated in short cycles on the same land provoke phytosanitary problems which may force more chemical inputs. However, the potential effects of cropping systems with emphasis on energy crops, i.e. maize and oilseed rape on the incidence and severity of stem base and root diseases of wheat have not been investigated thoroughly. We therefore analyzed the effects of varied percentages of maize and oilseed rape on stem base and root pathogens of winter wheat grown in four different cropping systems and rotations in two locations in Central and Northeastern Germany for three years. Our results demonstrate that short and intensive crop rotations with wheat combined with crops for bioenergy production do not necessarily enhance the risk by soil and straw borne diseases. Moreover, a suitable combination of wheat, oilseed rape and maize with adapted cropping methods (late sowing after maize, ploughing) can significantly mitigate the threat of stem base diseases in wheat. While disease incidence of sharp eyespot was always <5%, cropping systems had significant effects on the incidence and severity of eyespot, fusarium foot rot and take-all (in Northeastern Germany). Incidence of fusarium foot rot and take-all was significantly reduced by 70% and incidence of eyespot nearly to 0%, when wheat was planted after maize in a system with late sowing and ploughing, compared to wheat after oilseed rape with reduced tillage and early sowing. Further, these cropping systems with maize showed a low level of fusarium head blight. DON levels in grains were always low. The present study demonstrates that current shifts in crop rotations to a higher prevalence of maize due to novel market developments do not necessarily enhance the phytosanitary risks in the main crop wheat, if a suitable system of agronomic measures is applied, enabling highly productive and sustainable energy crop production systems. (C) 2013 Elsevier B.V. All rights reserved.Agency for Renewable Resources (FNR) in Germany [FKZ 22022707
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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