1,720,980 research outputs found
Effective Treatments for the Successful Establishment of Milkweed (Calotropis procera L.) under Water Deficit
No full textThe application of superabsorbents to soils and seed coatings is a pre-sowing seed treatment method that is commonly used to improve early vigor and establish stability and uniformity under water deficit conditions. To evaluate the interaction of seed coating and superabsorbent on Calotropisprocera L. (milkweed) under water deficit conditions, a greenhouse experiment was conducted. The experiment was conducted with four coating material levels (non-coated seeds and seeds coated with peat moss, vermicompost, and canola residue), four growth medium levels (soil, sand + soil, soil + 2 g superabsorbent, and soil + 4 g superabsorbent), and three field capacity regimes (25, 50%, and 100%) in a completely randomized design factorial arrangement with four replications. Reducing the field capacity from 100 to 25% led to decreased growth (shoot and root dry weights and leaf area) and chlorophyll content. The activities of SOD, CAT, APX antioxidant enzymes, and proline increased under drought stress. The use of superabsorbent polymers in growth media enhanced growth indices and chlorophyll content and decreased the activity of antioxidant enzymes and proline under water deficit conditions. The highest chlorophyll and growth indices were observed when 4 g of superabsorbent was added to the growth medium under drought stress. The application of 4 g of superabsorbent to the growth medium reduced the activity of antioxidant enzymes and proline. The use of seed coatings improved the growth indices, antioxidant enzyme activity, and chlorophyll content under drought stress. The most adaptive morphological and physiological responses to water stress were observed in the vermicompost-coated seeds. The vermicompost coating containing a superabsorbent polymer (4 g/kg soil) proved to be the best for establishing milkweed under mild (50% FC) and severe water deficits (25% FC)
Effect of Heat Carrier Particles on Drying Characteristics and Germination Traits of Canola Seeds
No full textPurpose Research into hybrid drying methods is generally aimed at increasing drying speed while maintaining seed quality. Heat Carrier Particles (HCPs) can be used in fluidized bed drying to accelerate the seed drying process. However, this requires qualitative analysis of seed characteristics.Methods In this study, canola seed was mixed with HCPs to accelerate the drying process while maintaining seed quality. The HCPs were steel or glass beads (2.7 mm diameter) mixed with canola seed in proportions of 0%, 25%, 50%, and 100% at different drying temperatures (40, 50, and 60 degrees C). A fluidized bed dryer was used to monitor the drying process and then the germination ability of the dried seeds was evaluated in the experimental conditions.Results The drying time was reduced when the HCP content was 50% of the sample weight. However, drying time increased when 100% HCP was added. Also, the germination ability of the seeds decreased as the drying temperature increased. A higher proportion of steel beads caused a decrease in germination, while the glass heat carrier (50% at 40 degrees C) was best for maintaining germination in canola seeds.Conclusions The germination rate, shoot length vigor index, root length vigor index, and germination energy were significantly affected by the amount of HCP and the drying temperature. The germination parameters were highest when glass HCP was used, and the drying time was also reduced to an acceptable level in this treatment. The most suitable temperature and percentage of HCP were 40 degrees C and 25% of glass HCP in sample weight, respectively
The Reinforcement of Early Growth, Extract, and Oil of Silybum marianum L. by Polymer Organic Cover and Bacteria Inoculation under Water Deficit
No full textEarly growth water stress reduces the extract and fresh oil of Silybum marianum L. (S. marianum) shoots. Two experiments were conducted to reduce the effects of early growth drought. Treatments in the first experiment were organic seed cover fillers at three levels (control, vermicompost, and peat moss), hydrogel at seven levels (control, 2, 4, and 6 g hydrogelF1 per kg OSC, and 2, 4, and 6 g hydrogelA200 per kg organic seed cover), and water deficit at three levels (100, 50, and 25% of field capacity), and in the second experiment, seeds were inoculated with bacteria at four levels (control, Pseudomonas fluorescens, Pseudomonas putida, and their combination) and water deficit at four levels (100, 50, and 25% of field capacity). Our results showed that milk thistle seeds are sensitive to water deficit at the emergence stage. Covering milk thistle (S. marianum) seeds with organic seed cover increased water retention around the seeds and improved emergence percentage. Use of organic seed cover with hydrogel increased relative water content (RWC), leaf area, and shoot length, and increased extracts and oils in fresh shoots. Bacterial inoculation also improved initial growth and reduced the effect of water stress on the plant, and increased leaf number, extract, and oil. The combination of bacteria had a positive effect on initial growth and inoculation of seeds, P. fluorescens and P. putida increased relative water content (RWC), shoot height, and specific leaf area, and increased extract and oil under water deficit conditions. A comparison of the results showed that seed inoculation is a simple method without new culture medium, and improves extract and oil under water deficit conditions
Effect of Light, Temperature, Salinity, and Halopriming on Seed Germination and Seedling Growth of Hibiscus sabdariffa under Salinity Stress
Full text linkSalt stress is a serious and current global problem for crops. Due to climate change, the soil today has higher salinity levels than in past decades. Identifying temperature, light, and salinity that allow plants to germinate and grow is an ambitious challenge for the future. Hibiscus sabdariffa (H. sabdariffa) is a plant that undergoes abiotic stress during all stages of growth. The aim of this work was to identify the best conditions in terms of light, temperature, and salinity during the germination and growth phases of H. sabdariffa. To improve the germination of H. sabdariffa seed, the effects of abiotic stress were investigated in three experiments. In the first experiment, the factors included light at two levels (light and dark cycles) and temperature at eight levels (5, 10, 15, 20, 25, 30, 35, and 40 °C). In the second experiment, the effect of salinity was examined at seven levels (0, 30, 60, 90, 120, 150, and 180 mM NaCl). In the third experiment, the factors consisted of seed halopriming at two levels (0 and 180 mM NaCl for 24 h) and salinity at seven levels (0, 30, 60, 90, 120, 150, and 180 mM NaCl). The highest germination rate (GR), seedling dry weight, and uniformity of germination were obtained at 30 °C in dark conditions, as reported by one-way Anova analysis. Germination was restricted by temperatures lower and higher than 5 and 30 °C, respectively. By increasing the salinity, all the germination characteristics were decreased, but these effects were less pronounced by halopriming. The most suitable planting date was in the spring, when the temperature was in the range of 25–35 °C. During the germination stage, Hibiscus tea is sensitive to low salinity soils. Halopriming can be performed for enhancing GR and emergence percentage
Nano-Organic Coatings Improve Early Vigor of Brassica napus L. Seeds in Water Deficit
Full text linkLow emergence and vigor of canola seeds are common problems encountered by canola growers. Seed coating is a good way to solve this problem. The objective of this study was to find the best combination of nano-organic to be used as a coating for seeds for strengthening the absorption of water and emergence seed of low vigor canola. The treatments in the first experiment included six levels of organic coatings: 20% vermicompost with 80% bentonite, 30% vermicompost with 70% bentonite, 40% vermicompost with 60% bentonite, 40% residues of canola with 60% bentonite, 30% residues of canola with 70% bentonite, and 20% resides of canola with 80% bentonite. The results indicated that 20% residues of canola and 20% vermicompost had the highest moisture under the saturation conditions and kept moisture for a longer time. Subsequently, the factors of the second experiment included three levels of water stress (100, 75, and 50% field capacity (FC)), three levels of seed coating (control, vermicompost, and canola residues), and three levels of titanium dioxide nanoparticles (0, 0.5, and 1 mM). The results showed that nano-organic coating improved emergence percentage and seedling traits while increasing superoxide dismutase, peroxidase, and catalase activities and decreasing electrolyte leakage. The highest ratios for emergence percentage (74.67), seedling vigor index (264.58), and leaf area (418) were obtained at the highest level of nano-titanium (1 mM). The highest rates of superoxide dismutase (53.44), peroxidase (30.68), catalase (5.35), chlorophyll content (51.05), and lowest electrolyte leakage (42.39) were observed in the highest level of nano-titanium (1 mM). Based on the results, we suggest the use of rapeseed residues with nano titanium oxide for rapeseed coating. The use of nanoparticles in current seed coatings is useful for reducing stresses in the germination and emergence stages
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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