Rootstock type determines tolerance of Chardonnay and Shiraz to long‐term saline irrigation. (22nd September 2014) - Walker, R.R.
Abstract Background and Aims The effect of rootstock on chloride (Cl−) and sodium (Na+) exclusion capacity and yield of Chardonnay and Shiraz was investigated in the final 2 years (2007/08 and 2008/09) of a long‐term (14‐year) saline irrigation trial. Methods and Results Chardonnay and Shiraz, on own roots and on nine rootstocks, were irrigated for the first 12 seasons with water of electrical conductivity (ECiw) of 2.1 dS/m, with 7.15 ML/ha the mean total applied. The final two seasons were years of water restrictions, where the vines were irrigated with water of (mean) ECiw of 1.65 dS/m at a seasonal application of 3.04 ML/ha. Vines on own roots had a relatively low yield, for example 2.0 kg/vine (Chardonnay) and 8.8 kg/vine (Shiraz), and a high concentration of both chloride and sodium in grape juice (>1000 mg/L for Chardonnay and >500 mg/L for Shiraz). Ramsey and 1103 Paulsen rootstocks produced a high yield of 11–12 kg/vine with Chardonnay, and Ramsey and C7 produced a high yield of 23.5–24.5 kg/vine with Shiraz. Chardonnay on C5 and Shiraz on C7 rootstocks had the lowest concentration of grape juice chloride and sodium (in each case <50 mg/L). Conclusions Yield, a measure of salt tolerance, was positively correlated with rootstock‐conferred vigour, measured by scion pruning mass. Neither yield nor pruning mass correlated with the concentration of either chloride or sodium in grape juice or in trunk wood, except that Shiraz yield correlated negatively with trunk wood Cl−. Significance of the Study This is the first long‐term (>10 years) study to compare the effect of rootstocks on the tolerance of Chardonnay and Shiraz to salinity.