1,720,957 research outputs found
Genetic and physiological studies of heat tolerance in hexaploid wheat (Triticum aestivum L.)
Get PDFHigh temperature is one of the major environmental constraints for wheat production globally. It puts significant pressure on the wheat industry around the world, compromising both the quantity and quality of wheat grain produced. The current study focussed on the impact of brief episodes of very high temperatures during vegetative and grain-filling stages of wheat development using a combined approach of plant physiology and quantitative trait loci (QTL) mapping. At grain-filling stage, wheat plants were exposed to a brief heat stress (3 days, 37/27 ºC) 10 days after anthesis and the plants evaluated for a number of morphological and physiological traits (Chapters 3, 4, and 6). At the vegetative stage (~ 4 weeks after sowing) plants were challenged with a brief heat treatment (2 days, 40/30 ºC), and growth and senescence related characters were monitored using automated imaging facilities and a SPAD chlorophyll meter (Chapter 7). In total, 37 bread wheat genotypes were evaluated for different heat responses during the grain-filling stage. Genetic variation was observed among wheat genotypes for various heat responses, particularly for single grain weight, chlorophyll retention, rate and duration of grain-filling, and water soluble carbohydrate content and mobilization (Chapters 3 and 4). Overall, the findings suggested that more than one adaptation process contributed to tolerance. Generally, genotypes with more stable grain weight under heat tended to have particular traits under stress, including the ability to maintain chlorophyll content and rate and duration of grain-filling, and stronger water soluble carbohydrate mobilization efficiency (Chapters 3 and 4). Therefore, these traits may provide appropriate selection criteria for improving heat tolerance in wheat. A genetic linkage map of a Drysdale/Waagan population was constructed using a 9K SNP array (Chapter 5) and used for QTL analysis (Chapter 6) of heat responses (evaluated using heat susceptibility index) at the grain-filling stage. A region on chromosome 3BS strongly affected heat responses of grain weight, stay-green related traits, grain-filling duration, shoot dry weight and harvest index, explaining 10 to 40% of the phenotypic variation, with Waagan contributing the tolerance allele. Most notably, the results indicated a strong genetic link between stay-green and grain weight maintenance under brief episodes of terminal high temperatures but a lack of a significant association between the Rht-B1 and Rht-D1 dwarfing loci and heat tolerance. Using high-throughput automated imaging facilities in The Plant Accelerator, considerable variation among 77 bread wheat genotypes was observed for growth rate and senescence responses to a brief heat stress at the vegetative stage (Chapter 7). A subset of 32 genotypes was also screened at the grain-filling stage (Chapter 3) which allowed a comparison of heat responses at these two developmental stages. Growth rate and senescence responses at the vegetative stage showed significant associations with grain weight maintenance and senescence responses at the grain-filling stage. These results suggested a physiological/genetic link between heat responses at the different growth stages, with implications for developing more efficient heat tolerance screening methods. The present work contributes to the understanding of physiological mechanisms of heat tolerance and its genetic basis in hexaploid wheat, and identifies assays with potential to assist heat tolerance studies and in breeding programs.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2015
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
Grain-filling rate improves physical grain quality in barley under heat stress conditions during the grain-filling period
Get PDFHeat stress is a primary constraint to Australia's barley production. In addition to impacting grain yield, it adversely affects physical grain quality (weight and plumpness) and market value. The incidence of heat stress during grain filling is rising with global warming. However, breeding for new superior heat-tolerant genotypes has been challenging due to the narrow window of sensitivity, the unpredictable nature of heat stress, and its frequent co-occurrence with drought stress. Greater scientific knowledge regarding traits and mechanisms associated with heat tolerance would help develop more efficient selection methods. Our objective was to assess 157 barley varieties of contrasting genetic backgrounds for various developmental, agro-morphological, and physiological traits to examine the effects of heat stress on physical grain quality. Delayed sowing (i.e., July and August) increased the likelihood of daytime temperatures above 30°C during grain-filling. Supplementary irrigation of field trials ensured a reduced impact of drought stress. Heat tolerance appeared to be the primary factor determining grain plumpness. A wide variation was observed for heat tolerance, particularly among the Australian varieties. Genotypic variation was also observed for grain weight, plumpness, grain growth components, stay-green and stem water-soluble carbohydrates (WSC) content, and mobilisation under normal and delayed sown conditions. Compared to normal sowing, delayed sowing reduced duration of developmental phases, plant height, leaf size, head length, head weight, grain number, plumpness, grain width and thickness, stem WSC content, green leaf area retention, and harvest index (HI), and increased screenings, grain length, grain-filling rate (GFR), WSC mobilisation efficiency (WSCME), and grain protein content. Overall, genotypes with heavier and plumper grains under high temperatures had higher GFR, longer grain-filling duration, longer green leaf area retention, higher WSCME, taller stature, smaller leaf size, greater HI, higher grain weight/plumpness potentials, and earlier flowering. GFR played a significant role in determining barley grain weight and plumpness under heat-stress conditions. Enhancing GFR may provide a new avenue for improving heat tolerance in barley
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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