1,721,018 research outputs found
Orchard management to preserve soil fertility and improve the efficiency of water and mineral resources
No full textAn appropriate orchard management is a necessary condition for high quality production with respect to environmental aspects such as a) organic matter depletion, which leads to the desertification phenomenon; b) water shortage; c) soil alkalinization and salinization processes; d) aquifers pollution; e) nitrogen and carbon gas emissions. In this paper we discuss the most appropriate practices to preserve soil fertility and improve the efficiency of water and mineral resources. Soil incorporation of green manure, pruned material and mature compost can play an interesting role in reducing the chemical inputs in agriculture, improving the organic matter content of the soil and restoring its biological fertility. As regards an efficient use of water, it is important to consider: training system, plant architecture and the different distribution of light in the canopy, as well as the irrigation system and its management. The knowledge of the uptake of mineral elements and their partitioning in the different plant organs during the annual cycle, and reserves accumulation and mobilisation is necessary in order to synchronise the supply of nutrients with plant requests. The use of fertigation is recommended, as it combines efficient use of water resources with rational use of fertilisers. Finally, referring to the present knowledge on the matter, we will point out topics in which it will be necessary to invest resources in the future research projects
I cambiamenti climatici e la gestione sostenibile delle risorse nel sistema frutteto
No full textLe coltivazioni sono sensibili ai cambiamenti del clima che possono determinare variazioni dei regimi pluviometri
(intensità e distribuzione delle piogge) e delle temperature (sia durante il periodo di riposo invernale che durante
la primavera-estate) Allo stesso tempo, il comparto agricolo è responsabile delle emissioni del 13% circa dei gas
serra Se contribuendo all’aggravamento della distruzione del clima. Pertanto, il comparto agricolo deve confrontarsi
sul versante dell’adattamento e della mitigazione dei cambiamenti climatici.
La presente nota focalizza i possibili interventi nel settore frutticolo per una gestione delle risorse acqua e suolo
più sostenibile, orientata all’attenuazione dei possibili effetti negativi dei cambiamenti climatici. Si riportano e si discutono
i risultati di prove pluriennali, condotte in ambiente semi-arido, su diverse specie arboree da frutto mettendo
a confronto due sistemi di gestione (sostenibile e convenzionale)
Calcium absorption and distribution in mature kiwifruit plants
No full textActinidia deliciosa (C.F. Liang et A. R. Ferguson L.) mature plants trained to “Pergola” system were grown in a semiarid environment located in Southern Italy. During the growing season measurements were carried out on sap-flow of canes grown in different light exposure (exposed and shaded) using the heat-balance method. The exposed condition (> 40% daily available PPFD) was maintained through summer pruning, while the shaded one (< 20% daily available PPFD) was obtained using a shading-net; meteorological data were recorded, too. At the end of growing season, calcium and potassium accumulation in leaves, fruits and shoots of exposed and shaded canes were determined. Throughout the season the sap-flow of shaded canes was on average 45% of the exposed one. At the end of growing season differences in calcium content were found in different organs of exposed and shaded canes. The calcium concentration in exposed and shaded leaves was about 3 g m-2 and 1.5 g m-2 respectively, while in fruit the concentration was 0.2 % D.M and 0.11% D.M. for exposed and shaded fruits. The results obtained indicate that a high level of light availability determine an increase in xylem stream in canes which is responsible for the increase of calcium accumulation in different organs. Besides this increase of fruit transpiration rate can improve fruit storage quality
Light influences transpiration and calcium accumulation in fruit of kiwifruit plants (Actinidia deliciosa var. deliciosa)
No full textCalcium (Ca) is an essential plant nutrient involved in determining fruit quality of several fruits, including kiwifruit. The objective of the present study was to evaluate the influence of light intensity on transpiration and water flow into fruit of kiwifruit (Actinidia deliciosa var. deliciosa, C.F. Liang et A.R. Ferguson) and the resulting effects on Ca accumulation. At fruit-set two light treatments were imposed on single canes. The exposed treatment was maintained through summer pruning, while the shade treatment was imposed using shade cloth. Fruit transpiration was measured on attached fruit using a portable photosynthesis system. The inflow of water into the fruit via the xylem was estimated from fruit transpiration and its relationship with fruit Ca accumulation determined. The concentration of Ca was measured in xylem sap extracted using a Scholander pressure chamber. Following the first 40–50 days after fruit-set (AFS) the cumulative xylem water inflow into the fruit increased exponentially in both treatments, but by the end of the growing season the total influx was 30% higher in the exposed treatment than in the shaded treatment, reaching 140 g per fruit. The shade treatment influenced the concentration of Ca, causing accumulation in the fruit to be about 50% of that in the exposed treatment. Our results suggest that transpiration is not the only factor controlling Ca transport, and that light also influenced the Ca concentration in xylem sap. Taking into account that auxin is able to stimulate Ca uptake and that light promotes the biosynthesis of auxin protecting phenols (hydroxycinnamic acids), a new working hypothesis is proposed: light, induces the biosynthesis of such phenols, indirectly decreases auxin degradation, and therefore, increases Ca accumulation
Growth and yield in irrigated and non-irrigated olive trees cultivar Coratina over four years after planting
No full textThis study aimed to verify the cumulative effects of water deficits over four years on canopy and root growth and on yield in olive trees cv. Coratina. The trials were carried out at Gaudiano di Lavello (N 41° 03', E 15° 42') on trees planted in 1992 at distances of 6 x 6 m. During the first year of growth all plants were irrigated when soil water potential at 35 cm depth reached -0.08 MPa. From the second year on no water was applied to part of the grove, while the rest was irrigated according to the criterion used in the first year. At the end of the first year the soil volume explored by roots was 0.5 m3 p-1; in the second and third years the irrigated plants explored 2.9 and 8.6 m3 p-1 respectively, compared to 2.3 and 5.1 m3 p-1 in the dry treatment. Leaf area after the first year of growth was 0.6 m2 p-1. In the three subsequent years the irrigated trees showed leaf areas of 1.9, 6.1 and 6.9 m2 p-1, respectively, against 1.2, 3.8 and 4.9 m2 p-1 for the dry plants. The root-canopy ratio was 0.19 (g g-1 of dry weight) in the first year, and in the second and third years 0.18 and 0.16 (g g-1) for irrigated plants against 0.28 and 0.25 (g g-1) for dry ones. Yield from irrigated trees was 131, 548 and 1460 kg ha-1, in the second, third and fourth years respectively, while non-irrigated plants produced 39, 100 and 1020 kg ha-1. The results show that water deficit reduced soil volume explored by roots, leaf area and yield. The most marked effect was on canopy growth, making for a modified roots-canopy ratio compared to irrigated plants
Characterization of training system in relation to water use efficiency in apricot and kiwifruit plants
No full textTrials were carried out in Southern Italy on apricot plants (cv. Tirynthos) trained to transverse Y and kiwifruit vines (cv. Hayward) trained to pergola. Leaf area, light availability and gas exchange measurements were performed during different times of the growing season on both orchards. In kiwifruit vines at maximum LAI (3.7), reached in July, the shaded leaves were 60% of the total. During the annual cycle, exposed leaves showed a photosynthetic rate 50 times higher than shaded ones, while transpiration rate was only twice higher. Average WUE value in exposed leaves was 20 times higher than in shaded leaves. Apricot trees reached maximum LAI (4.7) in July with 44% of the leaves exposed (> 40% of incident sunlight), 20% of intermediate leaves (20-40 % of incident sunlight ) and 36% of shaded leaves (<20% of incident sunlight). The transpiration and photosynthesis in apricot leaves showed the same behavior as in kiwifruit leaves. The exposed leaves showed a WUE 3 up to 8 times higher than that of shaded ones. Shaded leaves consume 19% and 38% of the total transpired water respectively in apricot and kiwifruit during the day and, if we consider the night respiration, they do not contribute in any way to the energy balance of the whole plant. Shaded leaves were not a source but another sink for the plant and through an appropriate choice of canopy architecture and its correct management, in particular with summer pruning, it would be possible to improve the daily carbon balance and WUE
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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