The influence of plant density and hedgerow height on grape and wine quality. Trial on Gamay vines in Leytron (Wallis, CH)

A study on plant density was carried out in 1994, using Gamay vines on the experimental estate of Agroscope Changins-Wädenswil Research Station ACW in Leytron (Wallis, Switzerland). Variations in plant density were obtained by adjusting distances between rows and plants and heights of hedges. At comparative yields per unit surface area, the sugar concentration in must wasn’t affected by increasing distances between rows and plants. The ratio of exposed leaf surface per kg of grapes (SFE/kg) was a valuable tool in explaining this absence of effect. A ratio of SFE/kg equal or higher than 1 m2 was obtained for the whole variants. No significant effects of plant density were noted on the pruned wood weights per plant, the weight of berries, bud fertility or on the components of must and wine acidity. Raising distances that separate the rows tended to reduce potassium level in leaves. From the wine-tasting point of view, the increasing distance between rows didn’t affect the wine quality, considering that a sufficient ratio SFE/kg was maintained on the whole variants.