Handbook for Irrigation of Wine Grapes in South Africa

Chapter 7

TABLE 7.11. Effect of pre- or post-véraison medium frequency irrigation, compared to high frequency irrigation throughout the season on midday Ψ S , cane mass, berry mass and yield, as well as juice and wine quality characteristics of three cultivars in a sandy soil in the Lower Olifants River region (Myburgh, 2011h, i, j & k). Data are means for two seasons. Cultivar Parameter RAW depletion pre-véraison→post-véraison 30%→30% 75%→30% 30%→75%

Sauv. bl. Pre-véraison Ψ S

(MPa)

-1.0 a* -1.1 a 1.2 a 1.6 a 12.2 a 3.42 b 43.2 b 52.3 a 53.3 a -1.0 a -1.1 a 6.9 a

-1.2 b -1.0 a 0.9 b 1.5 a 9.8 a 3.64 a 48.8 a 42.7 b 51.9 a -1.3 b -1.0 a 6.3 b

-1.1 a -1.4 b

Post-véraison Ψ S Cane mass (t/ha)

(MPa)

1.1 ab

Berry mass (g)

1.5 a

Yield (t/ha)

11.7 a 3.52 a

Juice pH

6.6 ab

Juice TTA (g/  )

Vegetative character (%)

42.0 b 53.4 a 48.8 b -1.0 a -1.6 b 0.9 a 1.1 a 8.7 a 3.86 a 57.5 a 45.7 a 29.3 a 51.1 a -1.2 a -1.7 b 5.2 a

Fruity character (%) Wine quality (%) Pre-véraison Ψ S Post-véraison Ψ S Cane mass (t/ha)

(MPa)

Merlot

(MPa)

1.0 a 1.2 a 8.9 a

0.8 a 1.2 a 7.9 a

Berry mass (g)

Yield (t/ha)

Juice pH

3.85 a

3.88 a

5.1 a

5.1 a

Juice TTA (g/  )

Colour (%)

52.3 a 42.4 b 20.9 b 44.2 ab

56.4 a 38.8 c

Berry character (%) Spicy character (%)

22.5 ab

Wine quality (%)

42.5 b -1.5 b -1.1 a

Shiraz Pre-véraison Ψ S

(MPa)

-1.1 a -1.2 a 1.6 a 1.2 a 13.0 a 4.15 a

Post-véraison Ψ S Cane mass (t/ha)

(MPa)

1.3 b 1.3 a

1.5 ab

Berry mass (g)

1.1 b

Yield (t/ha)

11.5 b 4.05 a

11.8 b 4.13 a

Juice pH

4.4 b

3.9 c

5.1 a

Juice TTA (g/  )

Colour (%)

78.0 ab

74.8 b 55.2 a 35.5 b 47.3 b

80.5 a 57.3 a 47.1 a

Berry character (%) Spicy character (%)

57.5 a

43.0 ab

Wine quality (%) 58.2 a * For each cultivar, values followed by the same letter within a row do not differ significantly (p ≤ 0.05). 50.9 b

IRRIGATION OF WINE GRAPES 201