1,721,043 research outputs found
Thermal time requirement and harvest time forecast for peach cultivars with different fruit development periods
No full textNon-linear models using growing degree hours (GDH), based on the choice of base, critical and optimum temperatures, have been successfully applied to calculate thermal time required for spring bud burst in deciduous fruit trees. The flexibility of the model can fit the wide range of temperatures that occur during the peach fruit development period (FDP), which takes place from early spring to late summer. In this experiment, fruit growth was studied in relation to thermal time accumulated from bloom to fruit harvest for peach and nectarine cultivars whose fruit development period range from 70 to 150 days. Thermal time was calculated in terms of degree days (DD) (base temperature 7 °C, and critical temperature 35 °C) and GDH (base temperature 7.5 °C, optimum temperature 26 °C and critical temperature 38.5 °C). Climatic and phenological data (bloom and harvest dates) were available for a minimum of three to a maximum of nine years. GDH showed a lower coefficient of variation and a higher predictive capacity, in terms of days, than degree days for all of the cultivars tested. Taking into account the whole FDP, the accuracy of the GDH model in predicting harvest time ranged from 1 day, in the early ripening peach cultivar 'Maycrest,' to 4 days in late ripening peach cultivar 'O'Henry.' An accurate early forecast of fruit harvest time was obtained using the GDH accumulated during the first 25-52 days of FDP, depending on the cultivar
Plant-based water stress sensing in two olive cultivars with different physiological responses to drought
No full textA large portion of modern olive plantings is dominated by one main cultivar (‘Arbequina’) planted at super high density (SHD, 1,500 tree ha‐1), leading to a dangerous reduction in olive biodiversity. Very few cultivars have growth and productive patterns that suit the SHD system requirements. Partial intensification and mechanization with several cultivars may represent the safest and easiest alternative. The efficient use of limited natural resources, such as water, in SHD systems, requires precise management. Continuous plant-based sensing is a promising approach to managing water, mainly tested on the cultivar ‘Arbequina’. In this study, we evaluated the sensitivity of two promising indicators of plant water status in two Sicilian olive cultivars differ in their level of drought tolerance: 1) the minimum daily output pressure (Ppmin) measured with the leaf patch clamp pressure (LPCP) probe and 2) the maximum daily relative growth rate difference (RGRrange) measured with fruit gauges. Based on the indicators trends, we defined four water status conditions and related them to specific midday stem water potential (Ψstem) thresholds. In addition, the relation between Ppmin and RGRrange highlighted a greater tendency of the more drought tolerant cultivar to maintain leaf turgor under water deficit. This was accompanied by an increase in daily variations of leaf turgor and fruit shrinkage, not observed in the less drought tolerant cultivar. These results suggest tailoring plant-based water management protocols on cultivar-specific physiological responses to water deficit
Relationship between Canopy Architecture and Fruit Quality on "Rich May" Peach Grafted onto "Penta" and "GF677" Rootstocks
No full textObservations on crop efficiency and fruit quality of peach trees of ‘Rich May’ grafted onto ‘GF677’ (peach x almond) and ‘Penta’ (Prunus domestica L.) rootstocks are reported. Results were related to canopy architecture parameters, particularly to scaffold branches, shoot and leaf blade inclination angles, to the pattern of light distribution, and to the area of sunflecks projected at midday on the ground. Trees grafted onto ‘GF677’ were more vigorous, in terms of trunk cross-sectional area, summer pruning weight and leaf area. Within canopy light distribution profiles were in agreement with foliage density, with a higher light interception observed in trees grafted on ‘GF677’. Within canopy variation of fruit quality was higher on trees grafted onto ‘GF677’ than on those grafted onto ‘Penta’. Fruit red skin colour and soluble solids content were consistently higher on trees grafted onto ‘Penta
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
Estimation of chilling and heat requirements of six sweet cherry (Prunus avium L.) cultivars
No full textWarmer winters without sufficient chilling due to climate change in Mediterranean regions represent a threat for deciduous fruit tree species such as sweet cherry (Prunus avium L.) with high chilling requirement, since it will affect fruit tree phenology leading to dramatic yield reduction and fruit industry income loss. Quantifying chilling requirements to overcome winter dormancy is crucial for identifying suitable cultivars for a given site, for predicting the necessity and timing applications of rest-breaking chemicals and the possible consequences of climate change. The aim of the following study was to determine the chilling and heat requirements of six sweet cherry cultivars grown in a germplasm collection field located in central Italy. The cultivars analyzed in this study were: ‘Kronio’, ‘Kordia’, ‘Galuciu Precoce’, ‘Ferrovia’, ‘Sandra’ and ‘Ciliegio D’Ottobre’. Historical temperature records and blooming dates were recorded in order to estimate the chilling and heat needs of each cultivar. Temperature-based models, developed by Richardson (1974) and Richardson et al. (1982) for peach, were used to calculate the chilling and heat requirement of the cultivars under investigation; the obtained results were compared with experimental data achieved from a parallel study conducted in controlled environment. The study in controlled environment was started using 2 years old cuttings collected in the abovementioned germplasm collection field. Several cuttings (50 for each cultivar) were artificially chilled in a refrigerated chamber at 6°C. Every 100 chilling hour intervals a sample of cuttings were transferred into a growing chamber at 26°C and flower development was rated weekly. ‘Galuciu Precoce’, ‘Kronio’, ‘Kordia’ and ‘Ciliegio D’Ottobre’ resulted to be the cultivars with low chilling requirements while ‘Ferrovia’ and ‘Sandra’ showed medium-high chilling requirements. Growth chamber experiment showed that, in all cultivars, the need of Growing degree hours (GDH) to achieve bloom was inversely related with chilling units (CU) accumulation. Only the cultivar ‘Ciliegio D’Ottobre’ showed an atypical pattern which required further investigation. From our field calculations, the specific chill accumulation requirements varied among cultivars, showing a minimum chill requirement value for ‘Kronio’ (700 CU) to a high chilling requirement of ‘Ferrovia’ (1200 CU). Field estimated chilling requirement values of each cultivar confirmed the growth chamber experiment results
Identification of Incompatible S-genotypes and molecular characterisation of Traditional Italian Sweet Cherry (Prunus avium) Germplasm
No full textUtilizzazione di modelli fenoclimatici ai fini della valutazione delle esigenze termiche del ciliegio nelle diverse fasi del ciclo di sviluppo annuale.
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