1,720,957 research outputs found
Influence of diesel spillage on the productivity of ipomoea batatas and lactuca sativa
Get PDFA dissertation submitted to the Department of Agriculture in fulfillment of the requirements for the Degree Master of Science and Faculty of Science and Agriculture at the University of Zululand, South Africa, 2013.The effects of diesel contamination in soil on the germination, growth and dry matter partitioning in Lactuca sativa (crisp head variety) and Ipomoea batatas (dagga variety) were studied at two diesel concentration ranges 0-30 and 0-6 ml/kg soil. The first experiment tested the effects of diesel concentration and age of diesel contamination in soil on the germination of L. sativa and I. batatas. The second experiment investigated the effects of diesel contamination in soil on the growth and dry matter partitioning in I. batatas and L. sativa.
The effects of diesel concentration in soil contamination on the germination of L. sativa and I. batatas varied with the diesel concentration and the age of diesel contamination in the soil. Diesel inhibited the germination of L. sativa and I. batatas in a concentration dependent manner, showing increased inhibition with increasing concentration of diesel contamination in the soil. Also, the critical concentration of diesel for toxicity on the germination of L. sativa and I. batatas increased with the aging of diesel contamination in soil. However, the influence of diesel contamination in soil on the germination of the two species diminished with the age of diesel contamination in soil, suggesting possible reduction in diesel toxicity over time. The germination of L. sativa was more affected by diesel contamination in soil than that of I. batatas.
The result of experiment two indicated that, after 14 weeks of growth, the plant height, number of leaves, stem lengths, root lengths and the leaves chlorophyll content of L. sativa and I. batata, were highly negatively correlated with diesel concentration in soil contamination. The effects of diesel contamination in the soil on dry matter partitioning of the two species also varied with diesel concentration in soil contamination. At low diesel concentration in soil contamination in soil contamination (0-6 ml/kg soil), allocation of dry matter to the shoot system was favoured resulting in high shoot: root ratio of 4.54 and
12.91 for L. sativa and I. batatas respectively. However, at diesel concentration in soil contamination 0-30 ml/kg, allocation of dry matter to the root was favoured, an indication of the effort of L. sativa and I. batatas to survive the phytotoxic effects of diesel hydrocarbons in the soil. The effects of diesel contamination in soil on the germination and growth of Ipomoea batatas were more pronounced on the germination and growth of Lactuca sativa.
It can be concluded that, the phytotoxicity of diesel contamination in soil on the germination and growth of L. sativa is markedly stronger than the phytotoxity of diesel on the germination and growth of I. batatas
Cathodic water invigoration of deteriorated orthodox seeds – implications on subsequent plant growth.
No full textDoctoral Degree. University of KwaZulu-Natal,Durban
Cathodic water invigoration of deteriorated orthodox seeds – implications on subsequent plant growth.
No full textDoctoral Degree. University of KwaZulu-Natal, Durban.Orthodox seeds deteriorate even when kept under the best of conditions leading to loss of germination, poor seedling growth. In this study, a novel approach via the use of cathodic water, an electrolysed form of calcium magnesium solution, was used to invigorate fresh and controlled deteriorated seeds of wild (Bolusanthus speciosus (Bolus) Harms, Combretum erythrophyllum (Burch.) Sond., Erythrina caffra Thumb.) and agricultural (Pisum sativum L., Cucurbita pepo L.) species. Other treatment solutions investigated alongside cathodic water were un-electrolysed calcium-magnesium solution and deionized water. Fresh seeds of the test species were controlled deteriorated to 50% germination (P50) at 40°C and 100% relative humidity. Thereafter, the seeds were invigorated with the treatment solutions. Fresh and un-primed controlled deteriorated seeds served as the control. In addition, to study the mechanism of invigoration, the effects of priming on the membrane stability index (MSI), amylase activities, lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were investigated. The effects of priming on the reactive oxygen species (ROS) scavenging enzymes superoxide dismutase, and catalase and DNA (concentration and purity). All priming treatments improved germination, emergence, growth parameters and subsequent seedling photosynthesis relative to the unprimed seeds. In general, cathodic water was most effective at invigorating seeds in the all test species. Also, controlled deteriorated seeds benefitted more than the fresh seeds treatments. Analyses of the lipid peroxidation products and antioxidant enzyme activities in invigorated seeds provided support for the hypothesis that the effectiveness of cathodic water in the invigoration of debilitated orthodox seeds derive from its ability to act as a potent antioxidant. This study, which is a novel approach at bringing the concept of electrochemistry into germplasm conservation via the use of cathodic water, has also confirmed the efficacy of cathodic water in invigorating debilitated seeds. This is especially critical for seeds containing traits that may be under the threat of being lost due to various reasons. The current study reinforces the strong potential of cathodic water in the recovery of aged germplasm and improved yield of orthodox seeded species
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
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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