Browsing by Author "Serra-Stepke, Ignacio M."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemInfluence of soil parameters and canopy structure on root growth and distribution(Stellenbosch : University of Stellenbosch, 2010-03) Serra-Stepke, Ignacio M.; Carey, V. A.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Viticulture and Oenology.ENGLISH ABSTRACT: Because of long-term climate changes, apparently associated with higher temperatures and fewer rainfall events, factors such as water-use efficiency and site selection for new cultivars are a matter of increasing importance for viticulture. Within this context, the root system is expected to play a key role. Its relevance to grapevine functioning is due to the numerous functions in which it is involved. In the light of this, the development of the root system is highly relevant to the viticulturist because of the fact that grapevine growth and functioning are dependent on the development of the root system. Differences can, therefore, be expected in terms of berry ripening on single grapevines of the same scion for situations with differing development of root systems, despite being grafted on the same rootstock. Root growth is influenced by several factors, among the ecological aspects. Soil parameters have a predominant influence on root growth and distribution but also annual root production can be altered by canopy manipulation. Due to the importance of root growth to the aboveground development of the vine, it is critical to gain understanding of the relationship between soil factors and root growth and distribution, and the central role that the subterranean environment plays in the concept of terroir. This study aimed to investigate the effect of selected soil physical and chemical parameters on root growth and distribution and to investigate whether having very different canopies influences root growth. In order to achieve these goals, two experiments were conducted; the first was performed in two commercial Sauvignon blanc vineyards each grafted onto Richter 110, non-irrigated, with two treatments: undisturbed lateral growth and complete lateral removal. The second study included the analysis of eight commercial Sauvignon blanc vineyards grafted onto Richter 99 and Richter 110 located in the Stellenbosch Wine of Origin District. Measurements of physical and chemical soil parameters, root growth and distribution, canopy growth and functioning, vine water status and berry composition were performed. The edaphic factors appeared to be one of the most important parameters that affected root development by changing soil water availability and possibly causing physical or chemical limitations on root growth. From the results of this study, it is clear that severe water stress and a pH (KCl) lower than 4.5 play a key role in the limitation of root growth. Due to the fact that most of the soils from the Stellenbosch Wine of Origin District, especially the subsoils, are acidic, this is a factor to consider before planting. On the other hand, the combination of favourable edaphic conditions, such as a subsoil pH of higher than 5.0, light- to mediumtextured subsoil and moderate water stress, allow increased growth of thin roots. However, the effect of canopy management on root growth cannot be discounted due to its importance in the variation of carbohydrate demand by competing sinks. This study showed that lateral removal done from when the berries are at pea size results in an increase in the number of thin roots (0.5-2.0 mm). The secondary leaf area represents at least the same leaf area as the primary leaf area in all the vineyards evaluated, which reveals the relative importance of the laterals in the total leaf area of the vine and the potential importance in terms of microclimate and leaf area available for photosynthesis. Studies of root growth should take the vineyard canopy architecture into account.
- ItemMadurez optima de la baya. La importancia del color(Sexto Sentido Comunicaciones, 2011-12) Deloire, Alain J.; Coetzee, Zelmai A.; Muller, M.(Nina); Brand, Jeanne; Van Der Rijst, Marieta; Serra-Stepke, Ignacio M.INTRODUCTION: The color of the berry is a new and important indicator to determine the optimum ripeness of the fruit for the different styles of white wine, because the hues can help predict the aromatic profiles of wines. ONe Of The MOST important and difficult tasks for a vintner and a winemaker is to predict the style of wine that can be obtained according to the characteristics of the grapes and winemaking process. Traditional indicators such as brix, tartaric and malic acids, titratable acidity, tannins, anthocyanins, and so on, are strongly associated with the taste of wine. but that’s not enough. being able to predict the style of wine based on the aroma would certainly prove useful. This is one of the reasons why the optimum ripeness of the fruit is still relevant within the scientific community and the wine industry
- ItemSistema radical de la vid : importancia y principales factores que lo afectan(Ciencia Ahora, 2010-07) Serra-Stepke, Ignacio M.; Carey, Vicoria A.