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Seasonal changes in soil respiration rates in olive orchards
No full textA field study was conducted on olive trees growing at two locations in Tuscany, Italy, to determine seasonal changes in soil respiration rates (Rs) under different conditions of soil moisture. The two orchards differed in cultivar, age, soil texture and soil management. The soil was managed by either periodic disking or permanent grass cover. Soil water availability was modified using drip irrigation. Soil respiration rates were measured using a closed-chamber system connected to an infrared gas analyzer at different positions around six trees in one orchard (three irrigated and three non-irrigated) and three trees in the other orchard. Seasonal courses of Rs were similar in both orchards, with maximum values reached either in mid-spring or autumn over the two years of study. Low Rs occurred in the summer under rain-fed conditions. In both orchards irrigation resulted in dramatic increases of Rs. Soil respiration rates of the orchard with a grass cover were higher than those of the periodically disked soil and, on an annual basis, we estimated 11.79 and 7.84 t ha-1 of carbon emissions out of the soil in the two orchards, respectively. Carbon emissions due to soil respiration of irrigated trees were 7% higher than those of rain-fed ones
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
Conducibilità idraulica in tralci di piante di vite colpite dal mal dell'esca
No full textNelle prove sono state considerate piante adulte di tre vitigni, Cabernet Sauvignon, Sangiovese
e Trebbiano toscano, ciascuno innestato su tre portinnesti: Franco (A), 1103P (P) e Kober
5BB (K). Su questo materiale è stata valutata la funzionalità dei fasci xilematici mediante il test
della traslocazione di un tracciante colorato in soluzione acquosa (azosulfamide 1%). L’esame
è stato condotto su tralci di piante di vite, sintomatiche l’anno precedente, prelevati prima e
dopo la comparsa dei sintomi di mal dell’esca e su tralci di piante considerate sane. I tralci sono
stati mantenuti nella soluzione colorata per 2-3 ore al termine delle quali sono state realizzate
sezioni ogni 10 cm subito osservate a uno stereomicroscopio dotato di fotocamera digitale per
l’acquisizione di immagini. Sulle foto delle sezioni trasversali, mediante analisi d’immagine è
stata stimata la percentuale dell’area xilematica colorata dal passaggio del tracciante (Image
tool 3.00). È stata inoltre misurata la porzione di tralcio percorsa dal tracciante.
La porzione dei tessuti xilematici dei germogli non appaiono interessati prima della evidenziazione
dei sintomi fogliari da ostruzione o impedimenti, mentre dopo la comparsa dei sintomi
fogliari il germoglio portatore delle foglie sintomatiche ha risposto in maniera diversa
a seconda del vitigno, in particolare qualche limitazione è emersa nel Trebbiano toscano, mentre nel Cabernet Sauvignon si ha una riduzione del flusso solo nelle piante che hanno manifestato una ripetizione dei sintomi negli anni, cosa che potrebbe aver determinato un indebolimento stabile della pianta
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
Incidenza del mal dell'esca su Cabernet Sauvignon, Chardonnay, Sangiovese e Trebbiano Toscano in Toscana
No full textDalle osservazioni compiute su quattro vitigni aventi tre combinazioni di innesto, disposti a blocco randomizzato
è emerso che il Cabernet Sauvignon è particolarmente più sensibile al mal
dell’esca, del Sangiovese e del Trebbiano toscano, mentre lo Chardonnay è risultato il meno sensibile. Le piante autoradicate, invece, manifestano sempre una minore incidenza di piante sintomatiche, a eccezione che sul Trebbiano toscano, mentre nelle combinazioni con 1103 Paulsen e con Kober 5BB si nota una maggiore percentuale di piante sintomatiche.
Osservazioni condotte in vigneti coetanei (10-13 anni) di Ansonica, Merlot, Sangiovese,
Syrah e Vermentino, presenti in Maremma, hanno chiaramente indicato la elevata sensibilità
del vitigno Ansonica, senza che tale sensibilità possa essere fatta risalire al diverso tipo di
potatura. La presenza di 10 combinazioni di innesto in un vigneto sperimentale di Ansonica
ha permesso anche di stabilire, nell’arco di un triennio, un diverso grado di sensibilità alla
sindrome del mal dell’esca. Più in particolare, le piante che hanno presentato una minore infezione cumulata sono state quelle innestate su 110 Richter mentre la maggiore presenza
di piante malate è stata registrata su Gravesac . La presenza non uniforme della sindrome
nel vigneto randomizzato non ha consentito di evidenziare differenze significative
tra gli altri portinnesti, anche molto diversi per vigoria e origine genetica. L’insieme delle
informazioni ottenute da questi rilevamenti induce a ritenere che la presenza dell’innesto è
fattore predisponente alla manifestazione dei sintomi classici e progressivi del mal dell’esca
(foglie tigrate, necrosi internervali, necrosi delle foglie, caduta delle foglie, disseccamento de
grappoli, e apoplessia ) mentre l’influenza del tipo di portainnesto non è sempre generalizzabile.
In qualche caso, in funzione della sua vigoria, appare fattore predisponente (1103P,
ad esempio); tuttavia, il Gravesac, che ha un vigore comparabile al 110R, diverge nettamente
per la maggiore presenza di piante sintomatiche. Nell’impianto del vigneto sarebbe consigliabile,
ove possibile, preferire vitigni più tolleranti alla malattia o, quanto meno, adottare
tecniche colturali idonee a prevenire la manifestazione della malattia
Gas exchange, stem water potential and xylem flux on some grapevine cultivars affected by esca disease
No full textThe effect of esca disease on gas exchange, stem water potential and xylem flux of adult grapevines of Cabernet
Sauvignon, Sangiovese and Trebbiano cultivars was studied over three growing seasons. Water relations were
measured at véraison and cluster ripening on three types of vines: i) healthy (control); ii) symptomatic and iii)
apparently healthy in the year of measurements but that had showed esca symptoms in the previous season. Xylem
flux was determined on cane segments by perfusion using a tracing dye before and after the appearance of esca
symptoms. Esca induced a marked reduction (about 70%) in carbon assimilation and stomatal conductance,
especially in Cabernet Sauvignon and Sangiovese. Esca did not affect the stem water potential. Gas exchange
parameters measured before the symptoms appeared in plants affected by esca were similar to those of healthy
plants. Measurements made one month before the appearance of the symptoms cannot be used as screening method
to determine whether the vine will show esca. No differences in dye translocation were found before the symptoms’
appearance. However, a decrease in xylem flux was measured in symptomatic vines of Cabernet Sauvignon. After
the appearance of esca symptoms, only the Trebbiano had a lower xylem flux than the healthy vines.The effect of esca disease on gas exchange, stem water potential and xylem flux of adult grapevines of Cabernet
Sauvignon, Sangiovese and Trebbiano cultivars was studied over three growing seasons. Water relations were
measured at véraison and cluster ripening on three types of vines: i) healthy (control); ii) symptomatic and iii)
apparently healthy in the year of measurements but that had showed esca symptoms in the previous season. Xylem
flux was determined on cane segments by perfusion using a tracing dye before and after the appearance of esca
symptoms. Esca induced a marked reduction (about 70%) in carbon assimilation and stomatal conductance,
especially in Cabernet Sauvignon and Sangiovese. Esca did not affect the stem water potential. Gas exchange
parameters measured before the symptoms appeared in plants affected by esca were similar to those of healthy
plants. Measurements made one month before the appearance of the symptoms cannot be used as screening method
to determine whether the vine will show esca. No differences in dye translocation were found before the symptoms’
appearance. However, a decrease in xylem flux was measured in symptomatic vines of Cabernet Sauvignon. After
the appearance of esca symptoms, only the Trebbiano had a lower xylem flux than the healthy vines
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