1,720,998 research outputs found
Estimation of cut butcher's broom (Danae racemosa (L.) Moench) foliage vase life through the measurement of leaf functionality
No full textCut foliages are ornamental items with a vase life longer compared to cut flowers and a storage period that can be extended for up to two months. The aim of this work was to develop a model of prediction for the estimation of butcher's broom (Danae racemosa (L.) Moench) foliage vase life based on chlorophyll a fluorescence measurement. After harvest, the cut foliage was first stored at 4 or 10°C for 28 days and after storage, it was transferred to 20°C in a controlled environment for vase life evaluation. The chlorophyll a fluorescence was monitored during vase life and the induction curve was used for performing the JIP test. The average vase life of cut butcher's broom at room temperature was 34 days and declined to 27-28 days without differences between 4 and 10°C after two weeks of storage. The JIP test derived indexed were correlated with the vase life of cut butcher's broom branches and were used for estimating the vase life. Among the chlorophyll a fluorescence-based indexes evaluated, the performance index (PI) was selected, as it showed a progressive decrement which was the positively correlated with the vase life of cut foliage. The PI gives an indication on the vitality of the leaf and its functionality. Generally, leaf senescence or stressful conditions can induce a reduction of the PI. The linear regression coefficient between PI and vase life was 0.75 for cut branches stored. For these reasons, PI could be used as a tool for quality evaluation and vase life estimation in the cut foliage industry and distribution chain
Effects of postharvest application of salicylic acid and benzothiadiazole on cut rose (Rosa hybrida)
No full textRose (Rosa hybrida) is among the most important species sold as cut flower. Its vase life is quite short and ranges from 6 to 10 days, depending on postharvest conditions. Flower and leaf senescence is the main responsible for quality losses and strongly affects the marketability of this ornamental item. Salicylic acid is a plant hormone playing a key role in flowers senescence acting at different levels. The aim of this work was to evaluate the effects of postharvest treatments on the quality and on the vase life of cut-rose flowers. Cut roses (flowers and leaves) were treated for 24 h with salicylic acid – SA and with a commercial formulation containing benzothiadiazole – BTH, which is a functional analogue of the hormone. During vase life, chlorophyll a fluorescence was monitored non-destructively in leaves. Samples (leaves and petals) were collected at the beginning of the trial (T0) and after 4 (T4) and 7 (T7) days at 20°C and destructive determination of phenolic index was conducted. Results showed that SA treatment was effective in extending the vase life of roses but did not affect the phenolic content. On the other hand, BTH significantly increased the levels of phenols, especially in leaves, but, at the same time, it negatively affected the quality of stems, probably due to an impairment of water uptake
Ethylene and plant hormones interplay in the regulation of petunia petal senescence
No full textFlower senescence is a fascinating natural process which represents the final development stage of flower life. Plant hormones play an important role in regulating the timing of flower senescence. Ethylene and abscisic acid (ABA) crosstalk affects the flower senescence and usually they accelerate the senescence rate, while the cytokinins are known to delay. The aim of this work was to study the effect of ethylene precursors or inhibitors on petunia petal senescence. Fully open petunia (Petunia × hybrida L. ‘Dreams Appleblossom’) flowers were placed in distilled water (control), 100 μM abscisic acid (ABA), 1 mM 1-aminocyclopropane-1-carboxylic acid (ACC), 2 mM amino-oxyacetic acid (AOA), 500 ppb 1-methylciclopropene (1-MCP), and 200 μM 6-benzylaminopurine (BAP). Ethylene production, ABA, anthocyanins, total carotenoids, and phenols were measured. Results showed that flower longevity was significantly reduced in the treatments with ACC and ABA. The ethylene production was strongly induced in ACC treatment immediately after 24 h and also increased in BAP treatment after 4 days. ABA instead increased in flower treated with ethylene inhibitors such as AOA and 1-MCP. The antioxidant compounds showed slight changes among treatments, but were not significant. In conclusion, data report that ethylene and ABA have an antagonist effect, but both lead to acceleration of petal senescence in petunia
Enhanced growth and photosynthetic efficiency in wild rocket (Diplotaxis tenuifolia L.) following multi-species microalgal biostimulant application
Full text linkFoliar spraying is a simple and efficient technique that enables targeted delivery of biostimulants directly onto plant surfaces, minimizing losses and environmental dispersion. Among biostimulant categories, microalgaebased formulations represent an eco-friendly solution to improve crop productivity, thanks to their richness in bioactive compounds and rapid growth in low-input systems. In this study, the crude extract of three green microalgae with high commercial value and broad biotechnological potential-Auxenochlorella protothecoides, Tetradesmus obliquus and Chlamydomonas reinhardtii-along with their consortium, was tested as foliar biostimulants for the first time on wild rocket (Diplotaxis tenuifolia L.) at an early vegetative stage. Plants received three sequential treatments, and physiological and biochemical responses were evaluated at 24, 48, and 72 h after the final application. Biostimulation led to up to 32 % increases in fresh biomass and significantly enhanced photosynthetic efficiency (Fv/Fm, PI), particularly in consortium-treated plants. The multi-step application also triggered a late and transient rise in antioxidant compounds (carotenoids and phenolics), potentially improving post-harvest quality. Remarkably, these effects were observed even in the absence of abiotic stress, highlighting the intrinsic biostimulant potential of the treatments. Notably, when the consortium crude extract was applied, higher chlorophyll content, nitrate accumulation, and enhanced nitrogen assimilation (indicated by lower delta 15N values) were also observed. These results suggest a compositional and functional uniqueness of the consortium, likely due to interspecies interactions. Overall, early-stage, multi-step foliar biostimulation with selected microalgal species or consortia represents a promising and sustainable strategy to improve crop performance and modulate quality traits in leafy vegetables
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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