The use of viticultural and oenological performance of grapevines to identify terroirs: the example of Sauvignon blanc in Stellenbosch

New Plant Breeding Techniques (NPBTs) have the potential to revolutionize the genetic improvement of grapevine. However, the practical application of these techniques is limited by several challenges, such as the difficulty in generating embryogenic calluses, maintaining their competence during in vitro cultivation, and regenerating plants without defects. To overcome these challenges, we conducted a study to test the effect of two treatments on callus cultures derived from different grapevine varieties, with and without embryogenic competence. The tested substances were Silver Thiosulphate (STS) an ethylene inhibitor, and Salicylic Acid (SA), an elicitor with different effects depending on the concentration of use beyond the ethylene inhibitor activity.

In the current viticultural context, global warming leads to advanced and possibly accelerated ripening which can alter the balance among desirable grape quality traits sought for winemaking. Evaluation of genetic material that displays delayed and/or slower ripening could uncover a potential “slow ripening” trait for incorporation into commercial varieties through breeding. In this study, we evaluated a white-fruited selection discovered in the Grape Breeding and Genetics program at E. & J. Gallo Winery that displayed an unusual ripening pattern compared to standard varieties. Vines of the slow-ripening selection did not differ in their visual appearance, water status or gas exchange characteristics compared to vines of its normal-ripening sibling.

Il a été souvent démontré (Seguin, 1970), que les meilleurs terroirs sont ceux qui présentent pendant la période de maturation du raisin, une régulation et une limitation de l’alimentation hydrique de la vigne. Si on s’intéresse aux facteurs influençant ce régime hydrique, on constate le rôle prépondérant du taux d’éléments grossiers non poreux qui limitent la réserve utile du sol en diminuant le taux de terre fine. De plus, ces éléments grossiers jouent également un rôle au niveau du pédo-climat thermique car leur conductivité thermique et leur chaleur spécifique sont plus élevées que celles de la terre fine. Ainsi le sol se réchauffera et se refroidira plus rapidement (Saini et McLean, 1967), (Gras, 1994).

The increase in temperature caused by climate change produces an earlier budbreak date that affects the vineyard, which generates a greater risk of damage by spring frosts.

Despite their trace concentrations, volatile sulfur compounds (VSCs) are an important category of flavour-active compounds that significantly contribute to desirable or undesirable aromas of many foods and beverages. In wines, VSCs in the form of polyfunctional thiols, notably 3-sulfanylhexan-1-ol (3-SH), 3-sulfanylhexyl acetate (3-SHA), and 4-sulfanyl-4-methyl-pentan-2-one (4-MSP), possess extremely low olfactory thresholds (≈ ng/L) and pleasant “tropical aroma” notes. They have received much attention with respect to their sensory contributions, quantitative occurrences, biogenesis, and thiol management through viticulture and winemaking. However, the fate of these potent volatiles are still not fully understood.