Interaction «training system x vigour» on Merlot. Comparison between vertical trellis and minimal pruning. First results

The purpose of this investigation was to compare classical training systems manually pruned, (Vertical Trellis; Open Lyre, Lys, Geneva Double Curtain, Umbrella Kniffin) with a no pruned training system, the Minimal Pruning, in interaction with two vigour situations (high and moderate) mainly dependant on the soil and plant water content. The study focused particularly on Minimal Pruning. Minimal Pruning on Merlot has increased the yield in both vigour situations while decreasing the berry size but mainly the total cluster number per vine. The berry composition of the (MP) in the two vigour situations is different, mainly for sugar, anthocyanins and acidity. The (MP) wine composition is also distinguished in relation to the vigour. The (MP) wine from moderate vigour is among the most concentrated such as the open Lyre one, but with a component of acidity; the (MP) wine from high vigour situation is far below all wines in terms of quality. Moderate vigour means a water limitation between –0,4 and –0,6 Mpa since véraison to harvest maturation according to CARBONNEAU (1998) scale of the predawn leaf water potential. The high vigour (MP) wine is less concentrated than the wines from all the tested training systems. (MP) in moderate vigour situation has a better cluster microclimate than (MP) in high vigour situation, what could also contribute to favorable berries ripening. In addition, for both, the clusters are less compact what is unfavorable to rots. Minimal Pruning in moderate vigour situations could be an attractive economical option for some range of wines as «vins de pays» or «vins de cépage» by reducing pruning expenses and total costs in general, that if vigour can be regularly controlled at a moderate level