The effect of vineyard management practices on pinot noir fruit and wine composition
thesisposted on 2023-05-26, 05:42 authored by Kerslake, FL
The current study was designed to investigate commercially feasible vineyard management practices across a range of intensities to evaluate the effects of these practices on Pinot Noir fruit and wine composition. Over three growing seasons, 2006, 2007 and 2008, two aspects of crop load management (node number retained at winter pruning and bunch removal) and two aspects of canopy management (leaf removal and shoot trimming) were investigated on a Scott Henry training system. To evaluate the effect on fruit and wine composition, individual treatments in the field were harvested, processed and fermented separately. Ferments were approximately 10 kg in size and winemaking was carried out at the micro winery at Tamar Ridge Estates' Kayena vineyard. Winter pruning levels of 10, 20, 30 or 40 nodes per vine were applied to the same vines for consecutive seasons. The bunch removal trial removed 20% or 40% of bunches at four different stages of the season: fruit set, pea size, 10% veraison and 90% veraison. In the 2006 season, 20% or 40% of leaves were removed on upper and lower shoots at four different stages of the season (fruit set, pea size, 10% veraison, 90% veraison). For the 2007 and 2008 seasons, four different leaf removal treatments were applied removing the basal four leaves, the middle section four leaves, the apical four leaves or removing no leaves on vines shoot trimmed to approximately 12 nodes on upper and lower shoots. The shoot trimming trial varied the length which shoots were trimmed to on upper and lower shoots. In the 2006 season, upper shoot length only was varied (6, 12 or 22 nodes per shoot) with approximately 12 nodes per shoot on lower shoots. For the 2006 and 2007 seasons, an additional treatment was added reducing lower shoot length to 6 nodes with 12 nodes per shoot on upper shoots. Yields varied up to three-fold as a result of pruning treatments, yet the predicted decline in fruit and wine composition as a result of increasing node number was only seen in seasons of cool weather conditions. Yield was varied 1.5-fold in the bunch removal trial and only in the season of cooler than average ripening period was bunch removal effective in improving fruit and wine composition. Leaf removal as a canopy management tool was effective for reducing Botrytis cinerea pressure, however little fruit and wine composition differences were seen between no leaf removal and the commercial standard of the removal of basal leaves in the fruiting zone. The shoot trimming trial indicated that reducing shoot length from the commercial standard was detrimental to fruit and wine composition, but increasing shoot length did little to improve wine composition. The influence of weather within seasons was found to override the effects of the viticultural management practices and the responses of fruit and wine composition could be interpreted within the context of the weather conditions of each season. During seasons of warmer than average temperatures, in particular during the ripening period, viticultural management of Pinot Noir vines had little effect on fruit and wine composition. In contrast, viticultural management in cooler than average seasons did affect fruit and wine composition and may repay the investment in terms of improved wine composition and therefore quality.
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