1,720,979 research outputs found
The potential of Citrullus colocynthis oil as a biocide against phytoparasitic nematodes
No full textThe high content of nematicidal fatty acids in Citrullus colocynthis seed oil could result in a novel product with a nematicidal potential. In this study, C. colocynthis oil was evaluated for its in vitro activity both against infective juveniles and eggs of the root-knot nematode Meloidogyne incognita and against infective specimens of the lesion nematode Pratylenchus vulnus, as well as against the suppressiveness of M. incognita in an experiment on potted tomatoes. The fatty acid composition of the tested oil was determined by gas chromatography analysis. Linoleic acid methyl ester (44.63%) and oleic acid (26.48%) were the two main fatty acid components, but there were also consistent percentages of erucic acid methyl ester (10.08%), palmitic acid (7.88%), and stearic acid (5.86%). C. colocynthis oil was highly toxic to M. incognita juveniles (>73% mortality) after a 24-h exposure to a 25 μg mL−1 solution, whereas infective specimens of P. vulnus were less sensitive with 46.6% mortality after a 24-h exposure to a 100 μg mL−1 oil solution. The viability of M. incognita eggs was strongly affected by C. colocynthis oil treatments with more than 64% egg mortality resulting from a 72-h immersion in a 250 μg mL−1 oil solution. Soil treatments with C. colocynthis oil resulted in a significant reduction of both M. incognita eggs and gall formation on tomato roots, as well as of nematode density in the soil, in comparison to the non-treated control. Tomato plant growth was not negatively affected by C. colocynthis oil treatments, though a slight increase in plant biomass was recorded at just the highest concentrations of oil. This research demonstrates the nematicidal properties of C. colocynthis oil and, thus, its potential for the formulation of new products that could be applied in the context of organic or integrated management of phytoparasitic nematodes
Long-term preservation of Cicer arietinum L. germplasm by in vitro propagation and cryopreservation
No full textChickpea (Cicer arietinum L.) is one of the most important pulse worldwide. This crop plays a significant role to maintain soil fertility through symbiotic N fixation, as well as in the Mediterranean diet for its important content of noble protein. In South Italy, particularly in the Puglia region, many traditional landraces are still cultivated in marginal areas, becoming therefore at strong risk of genetic erosion or even extinction. In vitro culture is a useful and innovative approach for the collection and the long-term preservation of threatened germplasm by means of the cryopreservation technology, as ex situ conservation strategy complementary to traditional ones. The aim of this study was to develop an efficient protocol for the multiplication and cryopreservation of two accessions of an Apulian black chickpea threatened landrace. Seeds of Apulian black chickpea were inoculated on agarized sucrose-free nutrient medium. The cotyledonary node and axillary buds were excised from the seedlings and then cultured on the same medium, supplemented with 6-benzylaminopurine and sucrose. After three subculture cycles, shoot tips from in vitro proliferated shoots were induced to rooting on IBA or used for germplasm conservation by comparing three cryopreservation techniques, i.e. PVS2-vitrification, droplet-vitrification and V-cryoplate. The results are very promising in terms of explant survival. However, the study should now progress to optimize a recovery medium, able to further improve shoot regrowth rates and plantlet formation in post-cryopreservation
Morphological, biochemical, and molecular analysis of Origanum vulgare L
No full textBackground: The variation on morphological, biochemical, and genetic characters is very important in germplasm management and conservation strategies. Objective: To determine the diversity of 23 accessions from Origanum vulgare L. and a commercial cultivar on the basis of agronomical, biochemical and genetic features. Methods: Different characters related to vegetative growth and essential oil production were studied while the genetic relationships between the individuals were evaluated with the use of Amplified Fragment Length Polymorphism. Results: Despite the accessions exhibited cymyl- and acyclic-compounds, all the essential oil chemotypes according to the prevalence of essential oil fractions were phenotypically varied. A considerable amount of biomass with maximum values in plant height was achieved by thymol/?-terpinene chemotype and carvacrol chemotype making them of particular interest for the production of high-quality plant material and further for the mechanical harvest. The AFLP analysis, performed using 10 primer combinations, to obtain a dendrogram of genetic similarity, revealed a genetic variability that could be useful for the selection of the proper genetic groups in future breeding programs. Conclusion: We identified two chemotypes thymol/?-terpinene and carvacrol with their suitability for the production of biomass and essential oil and for the mechanical harvest. The results of the molecular characterization of the species may support and contribute to breeding programmes for agronomic and biochemical traits
Somatic embryogenesis in Abies nebrodensis, an endangered Sicilian fir
Full text linkSomatic embryogenesis, as a promising biotechnological tool for many conifer trees, has never been applied for the Abies nebrodensis species. Although all the encouraging results previously obtained by the EU LIFE (European LIFE program) funded projects in over ten years, the critically endangered Sicilian fr remains alarmingly close to extinction. In this study, we reported the first protocol of somatic embryogenesis obtained from mature zygotic embryos of the Abies nebrodensis.
Seeds from Abies adult trees with specifc identifcation numbers (IN) were collected and full seeds were identifed by X-ray.
Diferent experiments were carried out for callus initiation, from both zygotic immature and mature embryos, testing diferent culture media. The immature embryos did not give embryogenic tissue (ET). Embryogenic callus (EC) was successfully induced from mature embryos with variable frequencies (0–40%). Schenk and Hilderbrandt (SH) was the most suitable initiation medium where the obtained callus initiation rate reached up to 40% for IN7 (frst experiment). 6-benzylaminopurine (BAP) showed to be essential to induce EC (second experiment). IN8 presented the highest callus initiation rate (40%) among all tested donor trees, whereas IN13 recorded the lowest rate with 4% (third experiment). ET maturation from each singular embryo of IN7, IN8, IN10 and IN21 was successfully achieved in SH medium containing 37,83 μM abscisic acid (ABA), 8% of polyethylene glycol (PEG-4000) and 4% maltose. The encapsulation technology was assessed on the obtained ET and its proliferation was observed after encapsulation
Essential oil diversity of Origanum vulgare L. populations from Southern Italy
No full textEssential oils (EOs) belonging to 25 wild populations of Origanum vulgare L. samples, growing wild in different locations of Calabria Region (Southern Italy), were analyzed using gas chromatography–mass spectrometry. The quantitative and qualitative data showed EO concentrations ranging from 0.96 to 5.10% and 37 compounds detected, representing more than 80% of the total composition of the oils. By applying hierarchical cluster analysis on the basis of the EO constituents, two main groups and three subgroups were found, reflecting the variation in the chemical composition of EOs from wild oregano populations. The first group consisted of acyclic (linalool/linalyl acetate) chemotypes with a predominant presence of linalyl acetate; the second was characterized by chemotypes rich in cymyl-compounds, mainly carvacrol, thymol and γ-terpinene. The data obtained contribute to broaden the inventory of wild oregano populations from Calabria to plan programs for the selection of chemotypes with new and specific uses
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
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