1,720,966 research outputs found
Effect of Pseudomonas fluorescens pCUGP and synthetic DAPG on biocontrol of Polymyxa betae/Beet Necrotic Yellow Vein Virus complex in sugar beet
No full textPolymyxa betae is an obbligate intracellular parassite and vector of Beet Necrotic Yellow Vein Virus, agent of rhizomania, an extremely severe disease of sugar beet.
2,4-Diacetylphloroglucinol (DAPG) is a wide spectrum antibacterial and antifungal antibiotic and a major determinant in the biological control of several plant diseases. It is produced by many strains of Pseudomonas both in vitro and in the rhizosphere of crop plants.
It has previously demonstrated that DAPG and P. fluorescens F113Rif pCUGP, a genetically modified strain iperproducing DAPG, is able to inhibit viability of P. betae zoospore and resting spore in microcosm.
In this work the protection efficacy of synthetic DAPG has been compared to that provided by GM-Pseudomonas, taking also into account the bacterial colonization levels obtained and the possible phytotoxic effect of DAPG, both in microcosm and in field.
In microcom experiments, at the lowest concentrations still affecting P.betae viability, synthetic DAPG showed phytotoxic effect that inhibits, in some extent, sugar beet seed germination and plant growth.
In the same condition, P. fluorescens F113Rif pCUGP efficiently colonized sugar beet rhizosphere producing a clear protection (although minor if compared with synthetic DAPG effect) against rhizomania. However, no phytotoxicity was observed.
Following these promising evidences, sugar beet seed, inoculated with P. fluorescens F113Rif pCUGP were sown in a field naturally infected by rhizomania, but no protection against disease was attained.
In open field condition, introduced strain appeared less able to colonize rhizosphere than resident pseudomonads population. Rhizospheric competitive-colonization ability, rather than the production of DAPG, seems therefore to play here the principal role in the efficacy of bioprotection. The possibility to increase colonization by improving the quality of the inocula (cell number and nature of the strain) and its application technique, is then discussed
Preliminary field test to assess the performance of the azospirillum-sorgum association in different crop management conditions.
No full textIn view of the release of 3 GM strains characterised for their ability to synthesize Indol-3-
Acetic Acid (IAA-, IAAn, IAA+++) an alternative experirnent with WT strains with different
ability in the synthesis of IAA was carried auto The evaluation of the effects of "natura!"
strains, somehow similar in this aspect to the GM to be tested would be helpull even
consideringt that A. brasilensSep 245, used in this study, is the base system to construct the
genetically modified strains.
The 3 WT strains provided, A. irakenseK BC1 (low IAA-producer), A. brasilenseS p245
(medium-IAA producer) and A. brasilense Sp7 (high-IAA producer) were compared to an
untreated contrai, under three different levels of nitrogen fertilisation (0,90 and 180 kg ha-l).
In order to evaluate the effect of IAA on the performance of the Azospirillum/plant
association multiple fiela' trial including different conditions or water supply and soil
managemen were also considered.
The experirnental scheme included a comparison between irrigation at 100% of restitution of root system in the first soillayer could have no beneficial effects, especially in very drought
conditions, such as thbse occurred this year.
These results could be related to the effect of IAA over-producer strains on root system, as
previously described for A. brasilense Sp6 I AA over-produce mutant, which affects the root
length density particularly in the first 0-30 cm soil layer. When water is a limiting factor (not
irrigated soil) the association with IAA producer azospirillum improves drought resistance
while when water is available (irrigated soil) a further development of the root system would
not provide benefits. Minimum tillage causes a greater development of the root system in the
upper soillayer compared to conventional tillage (ploughing
Evaluation of genetically modified microbial inoculants as biological control agents against rhizomania
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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