1,720,960 research outputs found
Virulence and pathogenicity of four Ditylenchus dipsaci populations on sugar beet
Full text linkThe stem nematode, Ditylenchus dipsaci, is a severe pest in European sugar beet production. In France, Germany, and Switzerland, D. dipsaci damage in sugar beet varies among specific geographic areas. In this study, the reproduction potential of four geographically distinct D. dipsaci populations was determined using sterile carrot disc cultures. In addition, virulence and pathogenicity were investigated in-vivo using sugar beet. No difference was found in the reproduction potential on carrot discs, as well as penetration rate in sugar beet seedlings. The reproduction rate in sugar beet tissue was significantly affected by the D. dipsaci population used. The population from Seeland (CH) showed the highest number of nematodes per plant at 60 dpi (21,071.8 ± 5340.0), compared to the three other populations contained 3588.6 ± 3858.3, 5136.9 ± 4950.8, and 3579.7 ± 5174.2, respectively. Furthermore, the reproduction rate of D. dipsaci was negatively correlated with fresh biomass of sugar beets at 60 dpi. Based on these results, the D. dipsaci population “Seeland” is suitable for breeding programs to detect resistance in sugar beet. After selecting candidate genotypes/varieties, these should be further evaluated for their field resistance in their targeted growing regions
Development of a new in vivo protocol through soil inoculation to investigate sugar beet resistance towards Ditylenchus dipsaci penetration
No full textThe stem nematode,Ditylenchus dipsaci, causes severe damage in sugar beet. To date, nematode inoculation throughthe leaf axil has been used as the standard method to investigateD. dipsaciinteraction with sugar beet underin vivoconditions. Toget as close as possible to field conditions, we established a new screening mechanism to perform soil inoculation. The most suitableinoculation time point, inoculum level and positioning on sugar beet, as well as rearing process on carrots, were determined. At a15:8°C day:night temperature regime, penetration rates ofD. dipsaciwere at maximum following soil inoculation at plant emergence.Up to 115 nematodes penetrated sugar beet seedlings 22 days post-planting with an inoculum level of 1000 nematodes into the soil atplant emergence.Ditylenchus dipsacipenetration rate was higher in plants with soil inoculation than with inoculation on to the leaf axil.High soil moisture increased nematode migration into seedlings whenD. dipsaciinoculation was carried out in four holes 1 cm fromthe plant base. Rearing the nematodes for 35 days at 20°C on carrot discs resulted in an infective inoculum containing up to 50% eggs.We recommend a soil inoculation of 1000 freshly extracted nematodes per pot at plant emergence. The nematode suspension has to bepreviously reared for 35 days on carrot discs to obtain activeD. dipsaciinoculum. This system will allow for the selection of suitablesugar beet genotypes that suppress nematode penetration, in support of breeding for resistance againstD. dipsaci
Screening of sugar beet pre-breeding populations and breeding lines for resistance to Ditylenchus dipsaci penetration and reproduction
Full text linkDitylenchus dipsaci is an economically important plant-parasitic nematode affecting European sugar beets. To date, no sugar beet cultivars carrying resistance against D. dipsaci are available to farmers. To find potentially resistant sugar beet lines restricting reproduction and penetration of D. dipsaci, three consecutive in vivo bioassays were carried out. The first experiment determined the penetration rate of D. dipsaci in 79 breeding lines and 14 pre-breeding populations. Based on these results, D. dipsaci penetration and reproduction resistance of eight genotypes was intensively investigated. It could be demonstrated that none of the genotypes showed resistance towards D. dipsaci. However, a high variation of the penetration rate by D. dipsaci was observed among the genotypes. The breeding line ‘DIT_119’ effectively reduced D. dipsaci penetration (34.4 ± 8.8 nematodes/plant at 22 days post-planting) compared to the susceptible control (109.0 ± 16.9) while ensuring a yield comparable to non-inoculated plants. However, the breeding line ‘DIT_119’ did not reduce D. dipsaci reproduction. The paternal line of the cultivar BERETTA KWS, demonstrating a high tolerance to D. dipsaci crown rot symptoms, did not reduce penetration and reproduction. Thus, no correlation can be established between reduced penetration rates, reproduction, and tolerance to D. dipsaci. This study provides an essential basis for the development of resistant sugar beet cultivars to D. dipsaci. The variations observed among genotypes now need to be confirmed with larger-scale screenings
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
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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