Shiraz and Chardonnay grapevines that had been initially assessed for Clexclusion in the 1996 and 1997 harvest seasons at both Merbein (inland region of Victoria) and at Padthaway (sub-coastal region of South Australia), were re-evaluated in 2003 and 2004 at those same two locations. Both scion varieties were grown either on their own roots or were grafted to one of the following rootstocks: Ramsey, 1103 Paulsen, 140 Ruggeri, K51-40, Schwarzmann, 101-14, Rupestris St George and 1202 Couderc. Both sites had been irrigated with saline water since 1994. The salinity of irrigation water at Merbein was approximately 2.1 dS/m; at Padthaway irrigation salinity varied between approximately 1.6 dS/m and 2.5 dS/m during the survey period. Changes in the Cl --excluding ability of all rootstock/scion combinations between 1996, 1997 and 2003, 2004 were based upon analysis of Clconcentrations in grape juice and in laminae at harvest, as well as Electrical Conductivity (EC), pH and Sodium Adsorption Ratio (SAR) of the 1:5 soil:water extract. Taking juice Clas indicative of rootstock effectiveness for Clexclusion, and considering data from Merbein, our analyses demonstrated that overall means for Shiraz juice Clincreased from around 190 to 427 mg/L over the survey period (7 years). In Chardonnay grapevines at Merbein, overall mean concentrations of Clin juice increased from around 70 to around 225 mg/L over 7 years. Significant differences between rootstocks were evident, with some rootstocks at Merbein showing a diminished capacity for Clexclusion in 2003 and 2004. By contrast, in Padthaway there was no consistent deterioration in Cl --excluding capacity by rootstocks supporting either Shiraz or Chardonnay as scions. In 2004 there were significant differences between grapevines at Merbein and Padthaway in the concentration of Claccumulated, even though the mean soil EC 1:5 after harvest for 0-90 cm depth was the same at both sites, namely 0.4 dS/m. Containment of grapevine salinity at Padthaway (relative to Merbein) between 1996/97 and 2003/04 was most likely due to factors such as a lower volume of saline irrigation, double the rainfall and 27% lower pan evaporation.
Abbreviations and definitionsClchloride; dS/m conductivity in deciSiemens per metre; EC electrical conductivity; EC se electrical conductivity of saturation paste extract; Na + sodium ion; SAR sodium adsorption ratio; EC 1:5 , SAR 1:5 and pH 1:5 electrical conductivity, sodium adsorption ratio and pH respectively of the 1:5 soil:water extract.