Background and Aims Rootstock type is known to affect the response of grapevines to irrigation with saline water. Less is known, however, about the long‐term response. The aim was to compare yield, laminae and grape juice ion composition at flowering and harvest, respectively, wine ion and spectral composition and wine sensory attributes of Shiraz on own roots and five rootstocks at a site that had been assessed over a decade earlier. Methods and Results Rootstocks were Ramsey, 1103 Paulsen, 140 Ruggeri, Schwarzmann and 101‐14. The study occurred over four seasons, including three with small‐scale winemaking and two with sensory evaluation. Mean electrical conductivity of the irrigation water across all seasons was 1.84 dS/m. Frost reduced yield in 2007, with no significant difference between each root system genotype (RSG, a term encompassing own roots and rootstock). In the recovery season 2008, yield increased, without significant difference among RSGs, whereas in Seasons 2009 and 2010, yield on 140 Ruggeri and 1103 Paulsen was significantly higher than that on the other RSGs. Laminae chloride (Cl − ) concentration was unaffected by season, whereas season means for juice Cl − , potassium (K + ), calcium (Ca 2+ ) and phosphorus (P) concentrations ranged from 1.2–4.3‐fold higher in season 2007 (frost‐affected) than in the other seasons. Mean wine Cl − concentration exceeded wine sodium (Na + ) concentration and was highest on own roots and lowest on Schwarzmann and 140 Ruggeri. With one exception (101‐14), there was little change in the Cl − concentration between juice at harvest and finished wine in 2007, whereas in 2008 and 2009, the mean increase over RSGs was 2.0–2.4‐fold. There was a significant negative correlation between the wine Cl − concentration and palate attribute acidity. The trend in frost‐affected 2007 season was lower wine color density, total and ionized anthocyanins, and total phenolics, but higher color hue, compared with Seasons 2008 and 2009, based on means across all RSGs. Conclusions Sustainable yield performance of Shiraz under irrigation with water of around 1.8 dS/m is dependent on RSG. Strong links were established between RSG and wine sensory attributes and between wine spectral and sensory attributes and plant mineral element status. The significantly higher concentration of Cl − in grape juice in the frost‐affected season appeared to be a crop load effect rather than an effect on the amount of Cl − transported to the developing crop. Significance of the Study The study enhanced the understanding of the impact of RSG on the longer term sustainability of a Shiraz vineyard and demonstrated a role for rootstocks as a component of terroir. To our knowledge, this is the first study to demonstrate an effect of frost on Cl − concentration in fruit and wine.
Walker et al. (Thu,) studied this question.