An overview of geological influences on South African vineyards

This study was carried out on 24 vintages of Cabernet sauvignon and on 7 vintages of Merlot produced by two different Bordeaux growing areas. Proanthocyanidin monomers and oligomers, and several parameters of the proanthocyanidin fraction were analytically assessed.

The geology of the Western Cape testifies to the former existence of a late Precambrian supercontinent, its fragmentation, the closure of an ocean between the South African and South American continental precursors (Kalahari and Rio de la Plata cratons), the accumulation of marine sediments and limestones, and their compression during a collision between these cratons

Global warming is shifting vine phenology, resulting in a decoupling of phenolic and technological berry ripening. This is altering the balance of fruit traits, which is key relevance to winegrowers

As elsewhere, southwestern France vineyards face more recurrent summer heat waves these last years. Among the possibilities of adaptation to this climate changing parameter, the use of net shading is a technique that allow for limiting canopy exposure to radiations. In this trial, we tested net shading installed on one face of the canopy, on a north-south row-oriented plot of cv. Gros Manseng trained on VSP system in the PDO Pacherenc-du-Vic-Bilh. The purpose was to characterize the effects on the ambient canopy temperatures and radiations during the season and to observe the consequences on the composition of grapes and wines. Two sorts of net were used with two levels of obstruction (50% and 75%) of the photosynthesis active radiation (PAR). They have been installed on the west side of the canopy and compared to a netless control. Temperature and PAR sensors registered hourly data during the season. On specific summer day (hot and sunny) manual measurements took also place on bunches (temperature) and in different spots of the canopy (PAR). The results showed that, on clear days, the radiation is lowered by the shade nets respecting the supplier criteria. The effects on the ambient canopy temperature were inconstant on this plot when we observed the data from the global period of shading between fruit set and harvest. However, during hot days (>30°C), the temperature in the canopy was reduced during afternoon and the temperature of the bunch surface was reduced as well comparing to the control. A decrease of the maturity parameters of the berries, sugar and acidity, was also observed. Concerning the wine aromatic potential, no differences clearly appeared.

Aim: Regional characters relating to Shiraz in Australia are not well documented. This study aimed to characterize the sensory, chemical and climate profiles of wines from various Australian Shiraz producing regions.