Two types of plastic cover (LDPE + EVA and LDPE + HDPE) were tested to assess their radiometric properties and the influence on the vegetative and reproductive performances of 'Matilde' table grape. Films showed the same transmittance to short infrared waves, but LDPE + EVA had a higher transmissivity to visible, PAR and short infrared wavelength ranges of solar radiation, especially as for the « direct » light component. In comparison to the open field, covering increased GDD accumulation and advanced budbreak by 12 days (LDPE + HDPE) or 20 days (LDPE + EVA). Commercial ripening (14 °Brix) was advanced by 8 and 22 days, respectively. Must acidity was higher in open field than under LDPE + EVA. Yield per vine increased under LDPE + EVA, although not at a significant level; bunch mass was higher under LDPE + EVA than in open field. Berry mass was maximum under LDPE + EVA and progressively decreased under LDPE + HDPE and in open field. Under covering, the pruning cane mass increased by 63% with LDPE + EVA and 43% with LDPE + HDPE.Résumé : Deux types de couverture plastique à base de polyéthylène à basse densité, associé à du éthylènvinylacétate dans un cas (LDPE+EVA) et dans l'autre à du polyéthylène à haute densité (LDPE + HDPE), ont été testés en Italie du Sud pour connaître leurs caractéristiques radiométriques et leurs effets sur le cycle phénologique et sur la production d'un cépage, « Matilde », à raisin de table précoce. Les deux films ont la même transmittance aux infrarouges longs, mais le type LDPE + EVA transmet mieux la radiation solaire visible, le PAR et les rayons infrarouges courts, surtout en ce qui concerne le composant « direct » de la radiation. Par rapport au secteur du vignoble sans couverture, la somme des températures au-dessus de 10°C a été constamment supérieure jusqu'à la fin du mois d'août. Le bourgeonnement fut avancé de 12 et 20 jours et la maturité commerciale (14 °Brix) de 8 et 22 jours par LDPE + HDPE et par LDPE + EVA respectivement. Le rendement fut augmenté par LDPE + EVA mais ne fut pas modifié de façon significative ; la masse de la baie et de la grappe fut plus élevée dans le secteur couvert avec le film plus transparent par rapport à celui à base de LDPE + HDPE et surtout à l'air libre. Le bois de taille en fin de saison était supérieure de 63 et 43 % (respectivement pour LDPE + EVA et LDPE + HDPE) par rapport au plein champ.
Italy (2) CREA-Consiglio per la Ricerca e l'analisi dell'Economia Agraria-Unità di ricerca per l'uva da tavola e la vitivinicoltura in ambiente mediterraneo-Via Casamassima, 148 Turi (BA)
In red winemaking de-stemming is crucial since the stems contain polymeric phenolic compounds responsible for the astringency of wine. Wine such as Primitivo has low phenolic constituents and tannins and stems affect aroma, taste body and olfactory characteristics. The aim of the study was to evaluate the effects of presence of stems during fermentation on polyphenolic, volatile compounds and sensory characteristics of wine. Primitivo grapes vinified in presence of different percentage of stems: 100 % de-stemmed (D100), 75 % de-stemmed (D75) and 50 % de-stemmed (D50). Results confirmed that the wines vinified in presence of stems were higher in tannins, flavans, to vanillin and proanthocyanidins, colour intensity with lower anthocyanins. The presence of stems during fermentation conferred more structure and flavour to wines. They facilitated must aeration thus promoting synthesis of higher alcohols and ethyl esters by yeast. In particular, a higher content of hexan-1-ol, hex-3-en-1-ol and 2-phenyl ethanol in D50 and D75 gave the wines that suggest green grass, herb and floral. Wine from D75 seemed to be better than D50 in terms of volatile compounds as well as fruity, floral and balsamic components preserved, without any unpleasant taste of long chain fatty acids found in D50.
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