This project investigates the feasibility of using rootstocks to lower berry potassium concentrations ([K]) in Cabernet Sauvignon grapevines grown in the Coonawarra wine region. The overall aim is to achieve lower pH and higher titratable acidity in grape juice so as to maintain wine stability and bring down the cost of acid adjustment during winemaking. The objective is to provide new insights into the potential of particular rootstocks to modify K uptake by Cabernet Sauvignon grapevines grown in ‘Terra Rossa’ soil and their partitioning and accumulation into grape berries. To achieve this objective, the soils of a replicated rootstock trial located in the Limestone Coast of South Australia were characterised and plant tissue, grape and juice nutrient content were assessed at oenological maturity for 8 different rootstocks. Rootstock had a significant impact on cations of the vegetative tissue of Cabernet Sauvignon, with M5512 having the lowest petiole [K]. The concentrations of major cations in the berry were, however, not significantly altered by rootstock. While no particular rootstock stood out in its ability to limit Cabernet Sauvignon berry K accumulation, Börner berries tended to have slightly lower concentrations (< 10%) relative to vines on their own roots. Across the rootstocks, juice pH tended to increase with greater juice [K], while juice TA tended to decrease with greater juice [K]. It was found that juice titratable acidity was higher for the rootstocks 140RU and 110R, and juice pH tended to be lower for the rootstocks 110R, 140RU, M5512 and M5489. There was no effect of rootstock on total soluble solids.
|Place of Publication||Australia|
|Commissioning body||Australian Grape and Wine Authority trading as Wine Australia|
|Number of pages||32|
|Publication status||Published - 2019|