Grape composition and wine quality from salt excluding rootstocks and characterisation of the chloride exclusion mechanism

Abstract

Yield, juice and wine composition and wine sensory qualities of Chardonnay and Shiraz on own roots and a range of rootstocks in a saline environment at Padthaway, South Australia, were assessed, and the mechanism of chloride (Cl-) exclusion in grapevines was investigated.

Summary

Some Australian viticultural regions experience problems associated with high salinity in irrigation water, which in turn can lead to high soil salinities and consequent impacts on vine performance and wine quality. The Australian Food Standards Code currently imposes a limit of 607 mg/L of Cl- in wine. Whilst there is no current limit for Na+ in Australian wine, the maximum permissible levels in wine vary widely among countries, ranging from 60 mg/kg (Switzerland) to 500 mg/L (Canada). Rootstocks with capacity for salt exclusion and for quality wine production in a saline environment present a significant opportunity to mitigate the negative impacts of salinity in irrigation water and soil and to reduce Na+ and Cl- content of wines.

Previous studies on rootstock performance in areas affected by salinity have concentrated mainly on scion yield, basic grape and wine composition, pH , titratable acidity, concentrations of ions such as Cl-, Na+ and potassium (K+), and for red grape varieties, wine spectral properties such as colour density and hue, and total and ionized anthocyanins. Very few studies, to our knowledge, and none that we are aware of in Australia, have focused not only on these parameters, but also on the sensory properties of wines from the grapevines. This broader range of information will assist grape growers in regions affected by salinity to make informed decisions on rootstock choice.