Project title
Influence of rootstocks development and functioning on berry growth and ripening of Pinotage (Vitis vinifera L.).

Project leader
Serra, I

Institution
University of Stellenbosch. Department of Viticulture and Enology.

Team members
Deloire, A
Myburgh, P
Nieuwoudt, H H
Kraeva-Deloire, E

Project description
Grapevines are grafted onto rootstock mainly because of phylloxera problems. Irrespective of this, the influence of root growth and functioning on the plant physiology and biochemistry is basic. The roots have many important roles, such as anchorage of the plant in the soil; to supply the plant mainly with water, minerals, nitrogen (Fitter, 1987) and hormones (Davies et al., 2005; Dodd, 2005; Jiang and Hartung, 2008).
The root development and functioning are related to the type of soil and its composition, but are also dependent on the plant growth and functioning (Archer et al., 1988). The relationship between the root system and the canopy is mediated by the root-to-shoot signalling, which is a process where signal molecules (other than water and nutrients) are supplied by the root system regulating mainly the shoot growth and water use (Dodd, 2005). The intensity of the root to shoot ABA signal is regulated on four
different anatomical levels, namely the rizosphere, the root cortex, the stem and the leaves (Jiang and Hartung, 2008).
Pinotage is a red wine cultivar that is specific to South Africa and which has been well studied. These studies have mainly focused on wine composition characterisation (de Beer et al. 2006b & 2006c;
Rossouw and Marrais, 2004; van Wyk et al. 1979) and in technology for the production of quality wines (de Beer et al., 2005, 2006a, 2008a, b.; Marais, J. 2003a & 2003b; Schwarz et al., 2004).
Therefore, there is a lack of knowledge on the direct or indirect effects of the root development and functioning on the progression of berry growth and ripening. It is important to generate new knowledge on this topic, regarding to questions on vine functioning (Pinotage could be a model for that purpose among
the red cultivars). It is also important to generate information on Pinotage berry dynamic of ripening for the wine industry.
This study will help to gain an understanding on the role of rootstock and root functioning, at the plot, vine and bunch levels, in South Africa, on the progression of Pinotage ripening and harvest potentiality regarding as well the style of wine. This study has a particular relevance to the South African wine industry as Pinotage is a South African cultivar and is therefore mainly cultivated in this country and not elsewhere in the world. Information generated therefore will be unique.

- Record end -