1,720,978 research outputs found
Effects of Se-enrichment on yield, fruit composition and ripening of tomato (Solanum lycopersicum) plants grown in hydroponics
No full textSelenium appears to be effective in promoting plant development and delaying the onset of senescence.
Besides the effects on the metabolism and physiology of different crops, controlled increases in Se concentrations
enhance the health-related properties of the produce. To study the effects of selenium on
fruit composition and ripening physiology, an experiment was carried out on tomato (Solanum lycopersicum)
plants grown in hydroponics. Sodium selenate was added to the nutrient solution at a rate of 0 (control) and 1 mg Se L−1
. The selenium added to the nutrient solution was absorbed by the roots, and the Se concentration was higher in leaves than in fruits. The addition of Se did not significantly influence
the cumulative yield of tomato plants, but a delay in the onset of fruit ripening was detected, and the harvesting of control plants began earlier than in Se-treated plants. The addition of Se did not significantly affect the qualitative parameters with the exception of -carotene content, which was lower in red ripe fruit treated with selenium. Since -carotene accumulation is a ripening-related event in tomato, the lower amount of this compound may be associated with a general delay of ripening. This is confirmed by the reduced biosynthetic rate of ethylene, observed in Se-treated tomatoes, which also showed a reduced rate in colour change. This thus confirmed that ripening-related processes, such as the degradation of chlorophyll and the synthesis of carotenoids, are affected by selenium - with potential benefits in terms of storage and shelf-life. Our results showed that 100 g of tomato hydroponically grown with a nutrient
solution supplemented with Se provided a total of 58 g Se. Thus, the daily consumption of 100 g of enriched tomato does not lead to Se toxicity, but can even provide a rational Se supplementation. This suggests that the addition of Se in a nutrient solution is useful for producing tomatoes with greater beneficial properties for human health
Effect of Salt Spray on Six Ornamental Species
No full textMarine aerosol strongly affects the growth and development of urban, garden
and landscape plants. The few studies available are focused on the sodium chloride
effect on plant growth, usually applied in the irrigation water or substrate media. No
information is available on responses of plants to marine aerosol. Therefore, the aim
of this work was to evaluate the physiological responses of some species to sea water
nebulisation treatment. Species were selected among those that are commonly used
along the seaside and among those that might be potentially used. Plants were
bought from local nursery and species used were: Acacia cultriformis, Callistemon
citrinus, Carissa edulis microphylla, Gaura lindheimeri, Jasminum sambac, Westringia
fruticosa. Plants were placed in randomised block in greenhouse and treated once a
day for 5-10 seconds with sea water or irrigation water (control) using a nebulisation
system.
The effect of marine aerosol was studied by monitoring leaf chlorophyll a
fluorescence, chlorophyll content, and leaf area damage by image analysis.
Results were different among species. The effect of treatment was represented
by leaf necrosis, reduction of chlorophyll and chlorophyll a fluorescence. The
resistant species was Westringia fruticosa, while the intolerant species were A.
cultriformis and G. lindheimeri. Intermediate behaviour was observed in the other
species
Effects of Selenium Enrichment of Tomato Plants on Ripe Fruit Metabolism and Composition
No full textThe effects of selenium (Se) addition on production and quality traits of Solanum lycopersicon ‘Red Bunch’ were investigated. Se was added as sodium selenate at the rate of 0, 0.5 and 1 mg Se L-1 to the nutrient solution. Se was absorbed by roots and accumulated in leaves and fruits, and at the tested concentrations, it did not affect yield. Se concentration followed a gradient, decreasing from the basal
to the apical part of the plant. At red ripe stage, the fruits on the lower trusses accumulated higher amount of Se than the fruits of the higher trusses. ß-carotene and lutein significantly decreased only at 1.0 mg Se L-1. Lycopene increased either in 0.5 and, less markedly, 1.0 mg Se L-1-treated fruits where a pronounced increase in quercetin was also observed
Absorption of selenium by Lactuca sativa as affected by carboxymethylcellulose
No full textSeveral organic compounds of high molecular weight present in soil interact with selenium and may act as active binding agents affecting its availability in soil, and, consequently, selenium uptake by plants. This study is aimed at investigating the effects of polysaccharides on selenium speciation in soil and on selenium absorption by Lactuca saliva L. plants. Three-week-old seedlings were transplanted into pots filled with soil, and sodium selenite at rates of 1.5 and 5 mg Se kg(-1) of soil, or sodium selenate at a rate of 1.5 mg Se kg(-1) of soil were applied. Carboxymethylcellulose (CMC) was added to the soil at rates of 0, 3 and 30 mg kg(-1) of soil. After 48 and 110 d from transplanting plants were harvested, separated into root and shoot, and fresh and dry matter weights were recorded. Total selenium was determined in both soil and plant samples. A sequential extraction was used to investigate the different Se oxidation states and assess the availability of Se in soil after the final harvesting. Both selenite and selenate were absorbed by roots, but plants amended with SeVI+ showed higher selenium concentration than plants amended with SeIV+. Selenite appears to be less mobile than selenate both in soil and plants. The addition of carboxymethylcellulose to soil decreased the amount of selenium absorbed by plants. CMC interacted with Se, making it less mobile as evidenced by the increase in the insoluble fractions. The insoluble Se forms in soil may represent environmental Se sinks potentially available for plants if the substrate is re-used for subsequent growth cycles and selenium species are mobilized as a result of biological and chemical processes. (c) 2006 Elsevier Ltd. All rights reserved
Interception of phosynthetically active radiation, growth and production of bush bean (Phaseolus vulgaris L.)
No full text
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
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