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Verifica del metodo evapotraspirometrico nella programmazione irrigua a livello aziendale
Get PDFLa ricerca è stata condotta nel biennio 2000-2001 su coltura di melone in cinque località rappresentative delle principali aree irrigue della Basilicata con l’obiettivo di verificare l’attendibilità e la trasferibilità del criterio evapotraspirometrico nella programmazione irrigua aziendale. Per il computo del bilancio idrico sono state adottate le seguenti risoluzioni: sono stati utilizzati i dati agrometeorologici la temperatura, l’umidità dell’aria e la pioggia, rilevati dalle stazioni SAL (Servizio Agrometeorologico Lucano) dell’ALSIA, le formule di Blaney-Criddle, della Radiazione solare corrette secondo gli standard FAO e di Hargreves per il calcolo dell’evapotraspirazione di riferimento, ETo, e i coefficienti colturali, Kc, proposti dalla FAO (nel 2000 quelli del Quaderno 24 e nel 2001 sono stati calcolati dei nuovi Kc seguendo le recenti indicazioni riportate nel Quaderno 56).
Il metodo evapotraspirometrico è stato testato valutando in primo luogo la risposta agronomica della coltura nei cinque campi prova in funzione delle variabili irrigue adottate, l’accuratezza nella stima dei volumi specifici di adacquamento confrontando il consumo idrico della coltura stimato con quello misurato direttamente da una stazione lisimetrica ubicata in un campo prova e la quantificazione dell’errore dovuto alla variabilità spaziale dei dati climatici tra il campo prova e la più vicina stazione agrometeorologica di rilevamento. Il criterio evapotraspirometrico, ha confermato la sua fondatezza sia da un punto di vista metodologico che applicativo nella programmazione irrigua aziendale. I risultati conseguiti sono buoni ed incoraggianti; in particolare occorre segnalare che, dalle misure lisimetriche effettuate a Gaudiano, i consumi idrici stimati, ed i conseguenti volumi d’adacquamento, sono risultati appena del 16% superiori rispetto a quelli effettivamente misurati da lisimetro. E’ necessario evidenziare che, una scelta corretta sia delle formule di stima dell’ETo sia dei criteri di calcolo dei Kc, è fondamentale per una corretta applicazione del metodo di stima. Infatti, utilizzando i vecchi coefficienti FAO (Quaderno 24), è stata riscontrata una sovrastima dei consumi idrici pari al 42%.
Tutte le formule di correlazione per la stima dell’ETo, si caratterizzano per la presenza di coefficienti empirici di aggiustamento, la cui parametrizzazione andrebbe, quindi, opportunamente calibrata su scala locale, con riferimento alle aree climaticamente omogenee, migliorando, in tal caso, non di poco, la precisione del metodo evapotraspirometrico.
Dal confronto dei dati di umidità del suolo stimati sulla base del metodo evapotraspirometrico con quelli effettivamente misurati per via gravimetrica, l’evoluzione dello stato idrico del suolo stimato è risultato perfettamente rispondente a quello misurato (r2 = 0.94), a conferma della bontà della metodologia applicata. Si è osservata inoltre, una buona correlazione fra i parametri climatici (temperatura ed umidità dell’aria) misurati dalle stazioni agrometeorologiche del servizio SAL e quelle presenti in loco in alcuni campi sperimentali.
La resa media in peponidi del biennio di 42.6 t ha-1, con un contenuto in solidi solubili medio di 11.7°Brix, non si è differenziata statisticamente né tra le località né tra gli anni. Questo conferma, non solo la validità del criterio di programmazione irrigua in termini di risposta agronomica, ma anche la capacità della metodologia di adeguare i volumi irrigui alla variabilità climatica dei differenti areali di coltivazione.
I risultati conseguiti permettono quindi di affermare che il criterio di programmazione irriguo prescelto per tale servizio, potrà agevolare gli utenti nella pratica irrigua e disciplinare con più efficienza l’impiego della risorsa idrica a livello aziendale
Phenotipic responses of Vitis vinifera L. to a changing climatic scenario.
Get PDFBackground: Nowadays there is much discussion on climate change and its effects on both human activities and natural organisms. In cultivated plants the actions and interactions of climatic factors and mankind-induced changes in vegetative and reproductive structures are very complex and in grapevines have largely been ignored [2,4]. In particular, premium wine production is limited to regions climatically conducive to growing grapes with balanced composition and varietal typicity. For these high quality grapes production the required climatic conditions can be summarized: (i) an adequate range of temperature, without risk of frost damage or extreme heat events; and (ii) a good precipitation distribution of adequate intensity in winter and along the growing season.
Aims: in this abstract, we briefly discuss some consequences on yield and grape quality of the changing climatic context in a warm and arid area of the South of Italy.
Methods: Meteorological data were measured by an automatic weather station with sensors exposed in the standard position as recommended by the World Meteorological Organization [5]. The weather station belongs to the Servizio Agrometeorologico Lucano (ALSIA) and is sited in Metaponto (N 40° 20’, E 16° 48’). The effects of water availability on yield and grape quality was carried out in a five-years-old vineyard (Vitis vinifera L., cv. Aglianico) located in Montegiordano Marina (42°02’ N, 16°35’ E). Half of the plants (IRR) were fully irrigated, whereas the other half were not irrigated (N-IRR). In both the treatments, plant water status, gas exchange, photosynthetic efficiency and productive performance were determined.
Results: Within the last 30 years the annual average of the daily maximum and mean temperature increased of about 2°C, a breaking point can also be observed around the 1996 when temperature start to increment until another quite stable value (Figure 1).
The impact of high temperature was found to be negative in both productivity and grape composition in several varieties, even if the relationship between winegrape quality and thermal behaviour may differs by variety [2,4].In the vineyard, the berry temperature, is not just a function of air temperature, but it is more dependent by the absorbed solar radiation and convective heat loss. For example, dark berries in the sun and under low wind conditions can be up to 10-15 °C above air temperature. Sunburn is the most obvious sign of damage soon after a heatwave event and can drastically reduce yield and fruit quality in many fruit tree species and vegetables [2,4]. In field conditions grape berries of Chardonnay cultivar showed the first symptoms of sunburn necrosis two days after 5 of exposure at 40-43 °C and 43-45 °C and treated berries reached the maximum level of damage after 4 days from the treatment when about the 12.4% of cells died [1].
Annual precipitation also increased of about 100 mm, while the contribution to the annual rainfall of the winter season decreased of about 10% (Figure 1). Grapevine responds to arid condition through a decreases of stem water potential (N-IRR vines reached a minimum value of -1.52 MPa), yield per plant, cluster weight and total berry weight were also significantly lower in N-IRR vines respect to IRR ones. Moreover, the lower soil water availability determined a marked shift toward the lighter and smaller berries volumes, and induced significant changes in other morphometric berry parameters. Total anthocyanins extracted from berry skins were significantly higher in N-IRR than in IRR (12301.53 and 9585.52 mg kg-1 fresh berry skin, respectively) and appeared to be positively related to berry weight, whereas total flavonols were not significantly different between the two treatments. These results highlighted that drought stress did not determine decreases in grape quality but have a significant impact on yield. Such data can be of primary importance in environments where water availability is by far the most important limiting factor for plant growth [3].
Conclusions: In the Metaponto area the eleven warmest years of the 30 years records have all occurred since 1996, indicating a rapid warming trend. In the South of Italy, continued warming will increase the uncertainty of suitability for high quality grape production and may alter grape and wine quality. Changing precipitation patterns could aggravate the problem of drought and thermal stress on grapevine and soil salinity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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