1,720,971 research outputs found
Leaf area, light environment, and gas exchange in Montepulciano grapevines trained to Tendone trellising system
No full textCanopy light interception (CPFDInt), spectral irradiance, leaf water potential, gas- exchange and optical properties were
measured in an irrigated vineyard (Vitis vinifera L. cv Montepulciano) trained to the so-called tendone system in which leaf
area index (LAI) was varied by means of 50% (T50) or 75% (T75) cluster removal. The 20.5 t ha71 yield in the unthinned
treatment (UT) decreased by only 36% in T50 and by 52% in T75. LAI and CPFDInt similarly increased until summer
pruning when LAI was 1.75 m2 m72 in UT, and 25.6% or 62.2% higher in T50 and T75, respectively. The two thinned
treatments had only 12.4% higher CPFDInt than in UT (1167.1 mmol m72 s71) due to the increased leaf self-shading. The
red-to-far red ratio (R: FR) was as low as 0.10 below the canopy. Light-saturated CO2 assimilation (Amax) in June averaged
14.4 mmol m72 s71 in sun-exposed leaves, and 7.6 mmol m72 s71 in shade leaves. By contrast, the apparent quantum yield
of CO2 assimilation (fe) was not significantly affected by leaf position, averaging 0.029 and 0.070 mol mol71 in June and
October, respectively. Middle and low canopy leaves had only 27 or 6%, respectively, of the top canopy leaves actual CO2
assimilation rate
La misura della fotosintesi in campo – Innovazioni strumentali nei sistemi per singola foglia e intera chioma.
No full textPotenziale vegeto-produttivo del vitigno Montepulciano (Vitis vinifera L.) allevato a Tendone.
No full textBlack leaf–clips of a commercial fluorometer increased leaf temperature during dark adaptation under high solar radiation
No full textThe use of black leaf-clips for dark adaptation under high solar radiation conditions is reported to underestimate the
maximum quantum yield of PSII photochemistry (Fv/Fm) measured by the continuous-excitation fluorometer Pocket
PEA. The decrease in Fv/Fm was due to a rise in minimum fluorescence emission (Fo), probably resulting from increased
leaf temperature (Tl). In field-grown tomato and pepper, fluorescence parameters and Tl in the region covered by the
black leaf clip were measured in clipped leaves exposed to solar radiation during dark adaptation (clipped-only leaves)
and in clipped leaves protected from solar radiation by aluminium foil (shrouded clipped leaves). Results confirmed
significant Fv/Fm underestimates in clipped-only leaves primarily due to increased Fo. In one tomato experiment,
Tl increased from 30 to 44.5°C in clipped-only leaves, with a negligible rise in shrouded clipped leaves. In two
respective pepper experiments, Tl in clipped-only leaves increased from 27 to 36.2°C and 33 to 40.9°C. Based on the
results of this study, a clip-effect parameter (PCE) on fluorescence emission is proposed as the difference for Fv/Fm
(or –Fo/Fm) between shrouded clipped leaves and clipped-only leaves, which resulted to be 0.706 for tomato, and 0.241
and 0.358 for the two pepper experiments
Vegetative and Reproductive Growth Potential of ‘Montepulciano’ Grapevines Trained to the Tendone Trellis System
No full textA study was conducted to evaluate the vegetative and reproductive capacity of ‘Montepulciano’ grapevines trained to the Tendone trellis system. The study was conducted during 2001 and 2002 in a 6-year old drip-irrigated vineyard located in southern Italy. Vine density was 1,600 vines per ha. Three crop load treatments were imposed at fruit set: UT – unthinned control with approximately 70 clusters per vine (~ two clusters per shoot), T50 – in which 50% of the clusters were removed (~ one cluster per shoot) and T75 – in which 75% of the clusters were removed (~ one cluster every two shoots). Vegetative and reproductive growth was evaluated by measuring leaf area development, leaf gas exchange and water potential, canopy light interception and shoot and cluster growth. Leaf area development was measured by collecting shoots from mature vines on a monthly basis, beginning 15
days after budbreak until the end of September. Transmitted photon flux density (PFDt), on a 0.10 m by 0.20 m grid at the soil surface, and incident PFD (PFDi) above the canopy were measured with a Ceptometer (Decagon D., Accupar) to calculate the intercepted light (PFDin). Gas exchange parameters were measured on both shaded and sun-exposed leaves. Preliminary results indicate that vines trained
to the Tendone system have a high capacity to produce vegetation and fruit. Intercepted light reached a maximum value of about 80% at maximum leaf area index (LAI). Thinned vines had significantly greater shoot leaf area, LAI and PFDin as compared to the unthinned control. There were no differences among treatments regarding leaf water potential, photosynthetic rate and apparent quantum efficiency
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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