1,720,983 research outputs found
The Eddy Covariance Technique for Carbon Balance and Water Exchange Assessment in Biomass Crops
No full textPotentials advantages by the use of Eddy Covariance in biomass crop
Canopy and leaf light reflectance features in relation to water content in apple
No full textThe relationship between spectral light reflectance and leaf water content has been established for several species, giving a sound basis to the use of remote sensing technologies in water stress detection for natural vegetation and crops. Nevertheless, few data are available about fruit tree species. The leaf and canopy reflectance features as indicators of plant water status have been here investigated in apple trees cv Golden Delicious grown in pots under progressive water stress. While the reflectance in the visible wavelengths was stable, some increase in this optical signature was observed in the 900-1000 nm spectral band when relative water content (RWC) decreased from 90.4% to 85.4%. This last RWC corresponded to a noticeable plant stress evidenced by photosynthesis and water potential trends. The depletion in reflectance in the whole 900-1000 waveband dramatically increased when further decreases in RWC up to 40.6% were reached in detached leaves, highlighting the absorption rule of water in the near-infrared region. On the contrary, the information about a decreasing leaf water content and the occurring of stress status was not inferred by the whole-canopy spectral reflectance measurements
Soil moisture measurements: a comparison of instrumentations performances
No full textIt has long been recognized that reliable, robust, and automated instrumentation for the measurement of soil moisture content can be extremely useful, if not essential, in hydrological, environmental, and agricultural applications. A number of automated techniques or point measurement of soil water content have been developed to operational level over the past few decades. While each of those techniques has been individually calibrated by the gravimetric method, typically under laboratory conditions, there have been few studies that made a direct comparison between the various techniques, particularly under field conditions. This paper compares ECH2O probes, EC-5 both sensors based on capacitance measurements, developed by Decagon Devices and time domain reflectometer sensors CS616 Campbell Scientific Water Content Reflectometer, with gravimetric data and with each other, under field conditions. Data were collected during two field experiments characterized by different soils and a wide range of soil moistures, resulting from irrigation/drying cycle.
Results show that all the tested probes give acceptable results after being calibrated in the field. The capacitive sensors can be used in each type of soil with the same calibration equation, independently from depth, with root mean square error RMSE ranging between 2.5 and 3.6%. Time Domain Reflectometry probes showed a dependence on depth but a lower RMSE 1.6%
Attivita' ed effetti collaterali di microrganismi benefici applicati a lattuga in ambiente controllato.
No full textI microrganismi benefici utilizzati in agricoltura biologica possono instaurare interazioni con la pianta ospite in grado di proteggerla dalle malattie e di migliorarne la crescita e l’assorbimento di soluti e acqua. Quest’ultimo aspetto potrebbe peraltro divenire importante a causa di una prevedibile progressiva limitazione della disponibilità di acqua. Piante di lattuga sono state allevate in vaso, in ambiente controllato per temperatura, intensità luminosa e fotoperiodo. Le piante sono state trattate con formulati commerciali a base di Trichoderma sp., di Glomus sp., e di loro combinazioni anche con ulteriori microrganismi benefici. Per ciascun formulato, le applicazioni sono state realizzate secondo il seguente schema: alla semina; alla semina e al trapianto; alla semina, al trapianto e durante la crescita in vaso. Il consumo d’acqua è stato registrato mediante l’ausilio di appositi sensori per il contenuto volumetrico d’acqua nel suolo (VWC). Da parte nostra abbiamo inteso valutare contestualmente e in funzione del numero e del posizionamento delle applicazioni: l’attività dei prodotti contro Rhizoctonia solani inoculata al terreno successivamente e il loro effetto sull’utilizzo dell’acqua da parte della pianta. I dati ottenuti mostrano una maggiore attività dei prodotti quando sono stati applicati alla semina e al trapianto. La maggior parte dei microrganismi saggiati ha inoltre evidenziato un consumo d’acqua minore per unità di peso prodotto. I formulati a base di Trichoderma mostrano la migliore combinazione tra i parametri in prova
Indagine sui flussi di materia ed energia da vigneto e da terreno nudo nell’interfilare in un sistema viticolo dell’Italia Centrale.
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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
Carbon fluxes and yield variability of switchgrass in northern Italy: preliminary first year data
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