Effect of rootstocks on berry weight and pH, mineral content and organic acid concentrations of grape juice of some wine varieties

Abstract

The effects of rootstocks (Schwarzmann, Ramsey, Dog Ridge, Harmony, Freedom, K51-40, K51-32, 11OR, 140R, 101-14,1202, 1616, 1613, ARG1, 420A, S04, 5BB, 5A and Rupestris du Lot) on the pH and mineral and organic acid concentrations in grape berry juice of the scion varieties Riesling, Ruby Cabernet, Shiraz and Chardonnay were investigated by sampling mature berries from rootstock-scion trials situated at Loxton (South Australia), Nuriootpa (South Australia) and Rutherglen (Victoria). Ungrafted vines of Riesling, Ruby Cabernet and Shiraz had low to medium juice pH (3.03, 3.43, 3.56) while ungrafted vines of Chardonnay had high juice pH (3.74, 4.01). Harmony, Dog Ridge, Freedom and Rupestris du Lot rootstocks generally caused a high juice pH, whereas 140R, 1202,5A, SO4 and 101-14 rootstocks gave a low juice pH. Positive correlations were found between juice pH and juice potassium, malate and, in some cases, sodium concentrations. Tartrate concentration and the tartrate/malate ratio of juice and sometimes juice chloride concentration were negatively correlated with juice pH. The rootstocks' effects on juice pH could be attributed to changes in potassium and sodium concentrations or in the tartrate/malate ratio.