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Effetto di derivati dell'urea sulla radicazione avventizia in vitro di microtalee micropropagate di corbezzolo
No full textRiassunto
La radicazione avventizia è un passaggio chiave della propagazione vegetativa di specie di interesse forestale, agricolo, orticolo e ornamentale. Questo processo può essere stimolato mediante l’applicazione esogena di auxina ma il solo trattamento con auxine non è sempre in grado di stimolare la formazione di un apparato radicale funzionale. In questo lavoro è stato indagato l’effetto di due derivati ureidici di sintesi, coadiuvanti la radicazione avventizia, N,N’-bis-(2,3-metilenediossifenil)urea e 1,3-di(benzo[d]ossazol-5-il)urea, in microtalee recalcitranti di Arbutus unedo L.
Abstract
Adventitious roots are post-embryonic roots which arise from non-pericycle tissue in stem and leaves. Adventitious rooting is a key step in vegetative propagation of plants, as it is a prerequisite for the successful production of viable clones.
Many environmental and endogenous factors, such as temperature, light conditions, hormones and tissue maturity, may affect adventitious root formation.
Auxin has been shown to be intimately involved in the process of adventitious rooting. In fact, exogenous auxin application may stimulate this process in those cuttings in which it doesn’t occur naturally. But, sometimes, auxin alone isn’t able to reduce the woody plant recalcitrance and to achieve a high quality root system. Many efforts have been made to enhance rooting, investigating the effect of other natural or synthetic molecules. Two urea derivatives, the N,N’-bis-(2,3-methylenedioxyphenyl)urea and the 1,3-di(benzo[d]oxazol-5-yl)urea, that do not show any biological activity per se, can act as adventitious rooting adjuvants in several rooting systems. Here we report the effect of these compounds in recalcitrant strawberry tree (Arbutus unedo L.) microcuttings. Our results confirm the activity of these two compounds as enhancers of in vitro adventitious rooting process, in the simultaneously presence of exogenous auxin
Cyclamen persicum Mill cv. 'Halios': Somatic embryogenesis and phenotypic analysis of somatic embryo-derived plants
No full textCyclamen persicum Mill cv. 'Halios' is a commercial cultivar that is mass produced as pot-plant using F1 hybrid seeds. One of the best and efficient way to propagate in vitro this plant is to induce somatic embryos from callus. Immature ovaries at different stages of development, taken from mother plants, differing for the colour of the petals, were induced to form embryogenic callus into the medium suggested by Schwenkel and Winkelmann (1998). The juvenility of the explants was confirmed to be important for inducing pro-embryogenic masses. It was observed a clonal behaviour in the callus lines obtained: the calli showed different colour and compactness and also a different embryogenic potential. The genotype "white" (line or clone H VII) showed the highest potentiality to produce somatic embryos. The somatic embryos of all the embryogenic genotypes were able to mature, to germinate and to develop into complete plantlets, which were then transferred in vivo. In order to evaluate the homogeneity of the crop, for excluding somaclonal variation events, morphological features as plant height, leaf length, open flower height and petal number were measured. The results show a high homogeneity of the somatic embryo-derived plants that can be considered "true-to-type plants"
Cold storage does not affect ascorbic acid and polyphenolic content of edible flowers of a new hybrid of sage
No full textThe effect of cold storage was studied on flowers and leaves of a new hybrid of Salvia pot-cultivated in Italy (Sanremo, Liguria). In particular, visual appearance, polyphenols, and ascorbic acid (ASA) levels were evaluated upon 6 days (d) of cold storage (5°C). Results showed as flowers and leaves were not affected by enzymatic browning till 6 d storage. ASA content, which was about 4-fold higher in leaves than in flowers, decreased in leaves (-43%) but not in flowers upon storage. Polyphenolic content was not negatively influenced by the storage in both plant tissues. This is one the first report in which the content of nutraceutical compounds was monitored in edible flowers upon storage. Obtained results indicate as flowers of this new Salvia hybrid are suitable to be merchandised in refrigerated sections of retail store in view of their high shelf life associated with high stability of nutraceuticals
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
Establishment of In Vitro Salvia Cell Biomass for the Controlled Production of Antioxidant Metabolites
No full textDietary consumption of foods rich in antioxidants has been gathering increasing support in recent years. The project NUTRASNACK (E.C. F.P. 6 contract No FOOD-CT-2005-023044), was developed to increase the antioxidant potential of food snacks. Several Salvia species and genotypes were tested for their total antioxidant content. Three genotypes with the highest antioxidant values were selected (S. officinalis 'SOF1', S. officinalis 'SOF2', and S. officinalis 'SOF3') and leaf explants of in vivo grown plants were cultured on modified MS media supplemented with 2,4-D, Kinetin and NAA in several combinations in order to induce friable callus. Friable green callus developed after five weeks in the presence of medium containing 0.5 mg L-1 2,4-D and 0.5 mg L-1 Kinetin. Callus was transferred several times to the same medium, and after three months, liquid primary cultures were established. After filtration, the synchronized cells grew rapidly and the growth parameters such as viability and growth curve in dry and fresh weight gave the essential information for the management of the cultures. The EC 50 of total antioxidant capacity was evaluated during all the growth phases of calli and suspension cultures
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