Handbook for Irrigation of Wine Grapes in South Africa

TABLE 7.8. Effect of high and medium irrigation frequencies on midday Ψ S , cane mass, berry mass and yield, as well as juice and wine quality characteristics of three cultivars under the same conditions near Lutzville in the Lower Olifants River region (Myburgh, 2011h, i, j & k). Data are means for two seasons. Cultivar Irrigation frequency High Medium Interval between irrigations ca. 3 days ca. 14 days Merlot Pre-véraison Ψ S (MPa) -1.0 a* -1.2 b Post-véraison Ψ S (MPa) -1.1 a -1.4 b Cane mass (t/ha) 1.0 a 0.8 b Berry mass (g) 1.2 a 1.1 b Yield (t/ha) 8.9 a 7.5 a Juice pH 3.9 a 3.9 a Juice TTA (g/  ) 5.1 a 4.8 a Colour (%) 52.3 a 58.2 a Berry character (%) 42.4 b 45.7 a Spicy character (%) 20.9 a 25.5 a Wine quality (%) 44.2 ab 53.8 a Shiraz Pre-véraison Ψ S (MPa) -1.1 a -1.4 b Post-véraison Ψ S (MPa) -1.2 a -1.6 b Cane mass (t/ha) 1.6 a 1.3 a Berry mass (g) 1.2 a 1.1 b Yield (t/ha) 13.0 a 10.4 b Juice pH 4.2 a 4.1 a Juice TTA (g/  ) 4.4 a 3.8 b Colour (%) 78.0 ab 82.8 a Berry character (%) 57.5 a 65.0 a Spicy character (%) 43.0 ab 45.8 a Wine quality (%) 50.9 b 58.7 a Sauvignon blanc Pre-véraison Ψ S (MPa) -1.0 a -1.3 a Post-véraison Ψ S (MPa) -1.2 a -1.6 b Cane mass (t/ha) 1.2 a 0.9 b Berry mass (g) 1.6 a 1.4 b Yield (t/ha) 12.2 a 10.0 a Juice pH 3.4 a 3.5 a Juice TTA (g/  ) 6.9 a 6.1 b Vegetative character (%) 43.2 b 48.6 a Fruity character (%) 52.3 a 32.7 a Wine quality (%) 53.3 b 56.8 a * For each cultivar, values followed by the same letter within a row do not differ significantly (p ≤ 0.05).

194 CHAPTER 7 – IRRIGATION STRATEGIES