1,720,956 research outputs found
Application of remote sensing techniques to discriminate the effect of different soil management treatments over rainfed vineyards in chianti terroir
Get PDFThe work aimed to discriminate among different soil management treatments in terms of beneficial effects by high-resolution thermal and spectral vegetation imagery using an unmanned aerial vehicle and open-source GIS software. Five soil management treatments were applied in two organic vineyards (cv. Sangiovese) from Chianti Classico terroir (Tuscany, Italy) during two experimental years. The treatments tested consisted of conventional tillage, spontaneous vegetation, pigeon bean (Vicia faba var. minor Beck) incorporated in spring, mixture of barley (Hordeum vulgare L.) and clover (Trifolium squarrosum L.) incorporated or left as dead mulch in late spring. The images acquired remotely were analyzed through map-algebra and map-statistics in QGIS and correlated with field ecophysiological measurements. The surface temperature, crop water stress index (CWSI) and normalized difference vegetation index (NDVI) of each vine row under treatments were compared based on frequency distribution functions and statistics descriptors of position. The spectral vegetation and thermal-based indices were significantly correlated with the respective leaf area index (R2 = 0.89) and stem water potential measurements (R2=0.59), and thus are an expression of the crop vigor and water status. The gravel and active limestone soil components determined the spatial variability of vine biophysical (e.g., canopy vigor) and physiological characteristics (e.g., vine chlorophyll content) in both farms. The vine canopy surface temperature, and CWSI were lower on the spontaneous and pigeon bean treatments in both farms, thus evidencing less physiological stress on the vine rows derived from the cover crop residual effect. In conclusion, the proposed methodology showed the capacity to discriminate across soil management practices and map the spatial variability within vineyards. The methodology could serve as a simple and non-invasive tool for precision soil management in rainfed vineyards to guide producers on using the most efficient and profitable practice
Ground vegetation covers increase grape yield and must quality in Mediterranean organic vineyards despite variable effects on vine water deficit and nitrogen status
No full textIn the context of a warming climate and widespread soil degradation, successful soil management practices in Mediterranean vineyards should combine environmental (e.g., soil health) and productive (yield and must quality) objectives. With this objective, we tested five soil management practices in two organic farms in Chianti Classico (Italy) across three years. Five treatments were compared: conventional tillage (CT), spontaneous vegetation (S), soil-incorporated cover crop of pigeon bean (Vicia faba L. var. minor (Peterm. em. Harz) Beck. L.) (PBI), a cover crop mixture of barley (Hordeum vulgare L.) and clover (Trifolium squarrosum L.), either mulched (BCM) or incorporated in soil (BCI). We explored the effects of soil management practices on vine stress (SPAD and stem water potential), grape production (yield per plant; number of clusters per plant; cluster weight; berries weight) and must quality (titratable acidity; malic acid; pH; sugar concentration; yeast assimilable N; potential anthocyanins and total polyphenol index). Soil variability was taken into account in the statistical analysis, by testing two sets of soil covariates. A first dataset included the “raw” electrical conductivity and gamma ray total counts. The second dataset consisted in a set of soil covariates obtained by combining data collected by the proximal sensors with the results of the chemical analyses. We found that soil management affected SPAD and stem water potential with variable effects between farms and years. Mulched cover crops showed lower vine SPAD values than tilled treatments at both farms, especially in 2019 and 2020, while spontaneous vegetation effects varied considerably across farms and were comparable to tillage. Conventional tillage also decreased vine water stress compared with S, especially at the colder site in 2020. Mulched cover crops and tillage treatments had similar vine stem water potential at the warmer site. Significantly higher grape yields were found under PBI and S (about +30% compared with the other treatments), mainly due to higher cluster weight. The most productive treatments (PBI and S) also showed higher pH and malic acid concentration but lower anthocyanins and total polyphenol index as compared with the other treatments. Conventional tillage increased yeast assimilable N in 2019 while S showed the lowest values, probably due to a drop in the abundance of N-fixing plant species. On a methodological side we found that including soil parameters as covariates, instead of ECa readings and gamma ray total counts, improved regression models for all the dependent variables studied except for juice pH. Overall, our results indicate that groundcovers induced only a moderate and temporary stress that affected grape production and quality differently. While the barley-clover mixture significantly reduced grape production irrespectively of termination type, S and PBI were associated with higher grape yields. Overall, this study demonstrated that groundcovers can be profitably introduced in vineyards also in Mediterranean climates with positive effects on yields and quality
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Development of a soil-crop water status Wireless Sensor Network to support the agrohydrological approach in the drought audit processes: first setups in Chianti terroir
Get PDFExploring the effects of vineyard soil management on spontaneous vegetation, soil health, vine growth and grape quality: preliminary results from Chianti Classico
Get PDFCover crops (CCs) can improve soil health and increase the provision of multiple ecosystem services from vineyards. However inter-row tillage is common practice in Mediterranean areas as vine growers are increasingly concerned about CCs competition for nutrients and water. As a result, intensive tillage has escalated soil degradation and to date vineyard is the land use with the highest soil loss rate in Mediterranean Europe. There is therefore a clear need to explore on-farm strategies able to strike a balance between improving soils and at the same time guaranteeing grape production and quality
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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