Delivering chloride and sodium excluding rootstocks for quality wine production

Abstract

Salt in irrigation water and soil is a concern in some Australian wine regions. Strategies for maintaining long term performance of grapevines in saline environments include use of salt excluding rootstocks to which wine varieties of choice are grafted. Performance of eight different rootstocks with a range in vine vigour was assessed in a salt affected region with Shiraz as scion. The rootstocks were 140 Ruggeri, 1103 Paulsen, 110 Richter, Ramsey, 101-14, Merbein 5489, Merbein 5512 and Merbein 6262 (hereafter referred to as M 5489, M 5512 and M 6262). Rootstock M 6262 was a relatively poor chloride (Cl‾) excluder. Wines of M 6262 contained 482 mg/L Cl‾ in 2012 and were characterised as having Salty taste and a perceived thickness of the wine on the palate (Viscosity), whereas wines of M 6262 contained 384 mg/L Cl‾ in 2013 and were not characterised as having Salty taste or Viscosity. Sodium (Na+) concentrations in wine from all rootstocks were relatively low (under 40 mg/L). Hence, Salty taste detection for red wines, based on the methods used in this study, occurred at wine Cl‾ concentrations of between 384 and 482 mg/L. The other seven rootstocks were similar in capacity for Cl‾ exclusion from grape juice, but there were differences between the rootstocks in final concentrations in wine (all under 175 mg/L Cl‾). A salt tolerance index (STI) for the various rootstocks was calculated based on yield, leaf area index, grape juice Cl‾ and Na+ concentrations and wine colour density. Best STI was obtained for M 5489, 110 Richter and 140 Ruggeri rootstocks and the lowest for M 6262.

Summary

The interaction between genotype, environment and management, including scion variety of choice, is a major factor determining the performance of rootstocks (Walker and Clingeleffer 2009). In development of new rootstocks, it is not possible to assess performance in all regions, in all soil types with all scion varieties. Hence, trials with new rootstocks, after limited release, are required in order to build information on their performance (Clingeleffer and Walker 2011). This study compared three new low to medium vigour rootstocks (M 5489, M 5512 and M 6262) with five standard rootstocks (Ramsey, 1103 Paulsen, 101-14, 110 Richter and 140 Ruggeri) in a region with good winter rainfall (approximately 450 mm), shallow soils over a calcareous layer, and limited available irrigation water (100 mm limit) which was moderately saline (1.8 dS/m). Vines planted in 2007 were assessed for juice ion concentrations in 2010-11. This was followed by a full analysis of vine performance over two seasons (2011-12 and 2012-13), including yield, yield components, leaf area index, juice and wine ion concentrations and wine sensory quality. The aim was to enable recommendations to be communicated to industry at the conclusion of the project.