Comparison of different techniques of soil management in Vitis vinifera L. cv Vermentino: viticultural, oenological and sensory aspects

Fabio Piras, Paolo Mulè, Massimiliano Giuseppe Mameli, Luca Demela, Donatella Delpiano, Roberto Zurru [Agris Sardegna]

Vineyard soil could be managed permanently or temporarily with conservative technique as the interrow sward, that could give environmental, practical and economic advantages compared to conventional tillage. The main limit to the large-scale application of the grass cover is the nutritional competition exerted by sward, especially in low soil water availability conditions, during the vegetative development phase because of the excessive reduction of the vine vigor and its effects on plant production and wine quality. These effects change depending on the growing environment, crop variables and vine varieties. The object of this research was to evaluate the effects of a conservative soil management (i.e. temporary interrow sward) on Vitis vinifera CV Vermentino vegetative and productive parameters in comparison to conventional tillage, in a vineyard grown in the Mediterranean climate of southern Sardinia (Italy). To discriminate better both soil management in comparison (temporary autumn-spring sward versus conventional tillage), two irrigation treatments have been carried out on each soil management: the author’s considered optimal water restoration (40% ETc) and the surplus water restoration (60% Etc). Four experimental treatments were obtained and repeated four times in a randomized block design. During the experiment nutritional status, plant vigour and productivity were measured while quality parameters were analytically evaluated on musts and wines, and sensorial parameters were evaluated on wines. Moreover, working time required for the two soil management application was estimated and showed a significant reduction in the case of sward treatment. Therefore, the interrow sward resulted easily managed and could be helpful to other cropping practices such as pruning, harvesting and pesticide spraying. Plants nutritional status resulted better in the plants managed with conventional tillage. The sward treatment, especially in less irrigation condition, induced a decrease in vine vigor without affecting plant productivity; moreover must showed higher sugar and polyphenols content and lower total acidity compared to conventional tillage. The must Yeast Available Nitrogen (YAN) resulted positively correlated with the surplus irrigation and with the conventional tillage soil management. As regards of wines no differences have been observed among treatments. However, conservative management treatment wines presented a greater alcohol content. Moreover, differences among treatments in the sensorial properties of wine were observed. Wines obtained by conventional tillage have been preferred for the more intense olfactory notes, greater minerality and less softness, which represent the main oenological characteristics to improve the Vermentino wine.

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