Handbook for Irrigation of Wine Grapes in South Africa

Chapter 7

PAW depletion before véraison did not improve sensorial wine colour, compared to high frequency irrigation throughout the season (Table 7.12). However, better colour, as well as more intense berry and spicy character, resulted in higher wine quality where the PAW was depleted to 90%, compared to 75% depletion before véraison. Similar to the Shiraz in the sandy soil near Lutzville, pre-véraison water constraints did not improve wine quality, compared to high frequency irrigation throughout the season (Table 7.11). Figure 7.17

100 120 140 160 180 200

A

FC

(40)

PWP (80)

0 20 40 60 80

Soil water content (mm/60 cm) Sep Oct

Nov

Dec

Jan

Feb Mar

100 120 140 160 180 200

B

FC

(40)

0 20 40 60 80

PWP (90)

Soil water content (mm/60 cm) Sep Oct

Nov

Dec

Jan

Feb Mar

FIGURE 7.17. Seasonal soil water content where Shiraz/110 R in a fine sandy loam soil was drip irrigated (A) at 70-80% PAW depletion before véraison followed, by 30-40% depletion during ripening and (B) at 90% PAW depletion before véraison, followed by 30-40% depletion during the 2008/09 season in the Breede River valley (Lategan, 2011). Dashed lines indicate field capacity, permanent wilting point and PAW depletion levels.

IRRIGATION OF WINE GRAPES 203