1,721,053 research outputs found
The effect of defoliation on the composition of xylem sap from Cabernet franc grapevines
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Nitrogen partitioning in apple trees as affected by application time
No full text15Nitrogen-ammonium nitrate was applied to four 'Mutsu' apple (Malus x domestica Borkh.) trees 40 days before harvest of 1996 (summer supplied nitrogen, SUN) and four others at full bloom in 1997 (spring supplied nitrogen, SPN) to evaluate the effect of application timing on N partitioning in mature trees. At leaf fall the largest amount of SUN was partitioned to roots and 2- to 4-year-old wood; the largest amount of SPN was partitioned to fruit and leaves and only a small amount detected in the roots. SUN did not increase N concentration in fruit or modify fruit firmness and soluble solids concentration, although it contributed to building up N reserves in the perennial woody organs. In 1997, as a result of the different timings of N supply, two sources of labeled N were distinguished and monitored in the vegetative organs: 1) the remobilized N, taken up in summer of 1996, stored in winter and then translocated to the growing tissues; 2) the newly absorbed N, taken up and moved to the canopy after the 1997 spring supply. Both fractions of remobilized and newly uptaken labeled N contributed to leaf and fruit N. Remobilized 15N was provided principally by roots which, from August to leaf fall, decreased their percentage of 15N by ≃18%, replacing the labeled with unlabeled N to maintain a constant concentration of total N
Carbohydrates, organic acids and mineral elements in xylem sap bleeding from kiwifruit canes
No full textIron content in vegetative and reproductive organs of nectarine trees in calcareous soils during the development of chlorosis
No full textWe investigated for 2 years (1995-1996) the time course development of chlorosis and the variation of iron (Fe) content in vegetative and reproductive organs in two nectarine orchards planted with cv Spring Red and cv Stark Redgold on calcareous soils of the Po valley (Italy) with the final aim to evaluate possible tools for the early prognosis of Fe chlorosis and a more efficient fertilization management. Due to the withdrawal of Fe supply, floral Fe concentration significantly decreased in 1996 as compared with 1995 in cv Spring Red, but not in Stark Redgold. Correlation coefficients between Fe and chlorophyll (Chl) from the same leaves were always higher when Fe was considered as amount present per leaf or per unit of leaf area than as leaf dry weight. The fact that chlorotic and green leaves had similar Fe concentration could be explained by an overestimate of Fe in the chlorotic leaf as a consequence of a reduction of its size. However, the decrease of Chl concentration between 60 and 120 days after full bloom (DAFB) occurred while leaf Fe content generally increased, indicating that even during chlorosis development leaves were supplied with some iron. We therefore suggest that the development of chlorosis was associated with an inactivation of Fe in the leaf apoplast. In 1995, regardless the cultivar, floral Fe concentration and leaf Chl were never correlated. In 1996 floral Fe concentration was linearly related to leaf Chl recorded 60 and 120 DAFB in cv Spring Red only. Floral Fe concentration at full bloom 1996, regardless the variety, was linearly related to leaf Chl determined in spring of the previous year, suggesting that flower Fe concentration might be used for assessing the storage of iron during the previous season. (C) 2000 Elsevier Science B.V
Nitrogen accumulation and leaf gas exchange in apple trees grafted on M.26 EMLA, M.9 EMLA and mark rootstocks under low soil temperature and drought stress
No full textTwo-year-old apple trees of cv Jonee grafted on Mark, M.9 EMLA and M.26 EMLA rootstocks were exposed for 10 days to low root temperature (8± 1°C) and drought stress to evaluate, over a 3-day period, the accumulation of labeled nitrogen (N) in root and scion and leaf gas exchange rate under adverse soil environment. M.9 EMLA showed a similar and a higher percentage of N derived from fertilizer (NDFF) in the xylem sap than M.26 EMLA and Mark, respectively. Unlike drought stress, low root temperature was effective in reducing NDFF in the xylem sap, compared to control trees. While not affected by rootstock, the labeled N removed by trees in control soil was similar and higher (P=0.09) than in dry and low temperature ones, respectively. Labeled N increased from Day 1 to Day 3 in the xylem sap as well as in the whole tree. Three days after N supply, most of the labeled N was accumulated in the root and less than 16% was detected in the shoot. A linear correlation was observed between the percentage of NDFF in the xylem sap and the amount of labeled N detected in shoot both one and three days after fertilization. Carbon assimilation (A) and transpiration (E) rates were higher in control, intermediate in low temperature and were lowest in drought-stressed trees. M.9 EMLA showed the highest A under optimal soil conditions but the lowest under drought stress. Low root temperature was more effective than drought stress in depressing N absorption while drought stress was more effective than low root temperature in decreasing leaf gas exchange
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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