1,721,014 research outputs found
Compost suppression of a fungal pathogen, Rhizoctonia solani, and its impact on root microbiomes
No full textComposts are not only beneficial to plants as available nutrients but for their suppression against pathogens such as the global fungal plant pathogen, Rhizoctonia solani. First, a plate competition assay and a suppressive colony assay were used to investigate the role of the soil microbiota in the suppression of R. solani by two different management techniques, anaerobic soil disinfestation (ASD) and vermicompost. R. solani grew more on agar plates with sterile soil than on plates with non-sterile soil, indicating the importance of the ASD and vermicompost microbiomes in R. solani suppression. R. solani was suppressed—indicated by zones of inhibition around colony forming units—by more bacteria than fungi. ASD soil contained more suppressive bacteria than vermicompost or untreated soil. Suppressive colonies of Actinobacteria from ASD and untreated soil were phenotyped for carbon utilization using Biolog EcoPlates™ and showed greater phenotypic diversity in ASD soils. Secondly, I characterize how incorporation of vermicompost and R. solani infestation of soil affects composition of soil and rhizosphere microbiomes and health status of radish (Raphanus sativus) plants. The composition of microbial communities in vermicompost and untreated bulk soil and rhizospheres were sequenced using 16S amplicons. Microbial community composition was influenced by sampling location (root vs. soil), amendment, presence of R. solani, and plant health status.Biological Sciences Program, CAL
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
Organic Amendments Alter Soil Hydrology and Belowground Microbiome of Tomato (Solanum Lycopersicum)
No full textManure-derived organic amendments are a cost-effective tool that provide many potential benefits to plant and soil health. For example, amendment applications may increase soil fertility, improve soil structure, stimulate microbial activity, and suppress plant pathogens. Yet, responses to these applications may have unintended consequences. Inherent variability in the physical, chemical, and biological characteristics of these materials can result in inconsistent outcomes observed after their application. These differences are manifested in plant growth, soil physiochemical properties, and soil microbial community composition. Popular manure-derived organic amendments include dairy manure compost and poultry manure pellets. Dairy manure is an abundant resource on many diversified farms and poultry manure pellets are an economical and commercially available source of nitrogen. Despite a growing body of research demonstrating the plant growth enhancing and disease suppressing potential of vermicompost, its’ relative price and availability has limited its widespread adoption in field-grown vegetable production systems. Additional research which determines how and why vermicompost performs differently than alternative amendments is necessary to justify its greater adoption. A container study was conducted to evaluate how dairy manure compost, dairy manure compost-derived vermicompost, and dehydrated poultry manure pellets impact the tripartite relationship among plant growth, soil physiochemical properties, and microbial community composition. Organic amendments increased soil porosity and soil water holding capacity but delayed plant maturation and decreased plant biomass. Of those treated with organic amendments, vermicompost-amended plants displayed the greatest root growth and overall plant health through time. Distinct microbial communities were detected for each treatment, with an abundance of Massilia, Chryseolinea, Scedosporium, and Acinetobacter distinguishing the control, vermicompost, dairy manure compost, and dehydrated poultry manure pellet treatments, respectively. Known ecological roles of these organisms support the observations made in this study: Massilia and Chryeolinea promote plant growth, Scedosporium abundance reflects the immaturity of the dairy manure compost provided, and Acinetobacter, among several taxa present in the poultry pellet-amended treatment, highlights existing concerns about the safety of poultry manure-based fertilizers in agriculture. This study validates that organic amendments alter the rhizosphere microbiome by influencing plant growth and soil physiochemical properties. In addition, this study highlights the impact of organic amendment application on the physical soil environment and the influence this change has, both directly and indirectly, on soil microbial community composition. Furthermore, this study demonstrates that there is a strong interaction between root growth and the spatial heterogeneity of soil and root-associated microbial communities. The varied response to organic amendment application in this study demonstrates that a more comprehensive characterization of these materials, and their impact on the soil environment, is required to successfully utilize these products in an effort to improve soil health and modify soil microbial communities. While highlighting a widespread need for additional research, this study serves to suggest that vermicompost is a valuable tool to promote plant health and manage disease and supports the adoption of a vermicomposting curing step to stabilize manure-derived fertilizer products.Plant and Soil ScienceMaster of Science (MS
Anaerobic Soil Disinfestation And Vermicompost To Manage Rhizoctonia Solani In Organic Lettuce
No full textRhizoctonia solani Kühn is an aggressive saprophytic soilborne fungal plant pathogen that is distributed globally and infects many crops including Solanaceae, Fabaceae, and Asteraceae. The lack of effective organic methods to control R. solani and the resulting yield losses contribute to the economic insecurity of farms and farmers. The overall aim of this study was to compare two organic certifiable approaches to manage bottom rot caused by R. solani (subspecies AG1-IB) in field-grown organic lettuce: anaerobic soil infestation (ASD) and thermophilic compost cured by vermicompost (vermicompost). A commercially available biocontrol product and an untreated control were used as references. Two concurrent, adjacent experiments were conducted at two commercial organic farms for two consecutive growing seasons in 2020 and 2021. Vermicompost and the biocontrol product RootShield® PLUS+G were incorporated separately into seeding starter media, sown with lettuce seeds, and 3-week plants were transplanted into unamended field soils. ASD treatments were implemented in situ on the farms and included an examination of four different soil amendments widely available and commonly used by local growers. Disease incidence, disease severity, and percent marketable yields were used to assess treatment success. Supplemental laboratory and greenhouse studies were conducted to confirm or refute the trends observed in the field. A farmer survey was conducted to quantify the economics of each practice and the likelihood of adoption. This study demonstrated that the ASD method is achievable in a field setting on Vermont vegetable farms but did not create disease suppression to compensate for the cost of materials and labor to establish. Vermicompost was less expensive and more effective than RootShield® PLUS+G. Neither ASD nor vermicompost were more profitable than standard growing practices. However, vermicompost is likely to be adopted by farmers in part because of the ease of treatment implementation and added soil health benefits. The findings of this study inform farmer’s best management practices and contribute to the body of research seeking effective tools to manage soilborne pathogens in commercial organic agriculture.Plant and Soil ScienceMaster of Science (MS
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
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
- …
