Deficit irrigation and canopy management practices to improve water use efficiency and profitability of wine grapes
Lategan, E L
Lategan, E L
Myburgh, P A
Howell, C L
Sassman, L W
In the Western Cape with the Mediterranean climate (winter rainfall and long dry summers), agriculture has to compete with urban and industrial needs for water. Consequently, irrigation water is a scarce resource. Considering possible climate changes, the worst case scenario would be if lower rainfall reduces natural water resources, and higher air temperatures increase the water requirements of vineyards. Even if climate change does not realize, grape growers still need to use irrigation water more efficiently, i.e. to maintain existing yields using less water or to produce more grapes with available water.
Excessively vigorous grapevine growth caused by injudicious irrigation has negative effects on wine quality. To obtain acceptable wine quality, canopy management of vigorous vineyards, need intensive labour which can be a expensive running cost.
The wine industry in the Breede River region approached the Soil and Water Science Division of the ARC Infruitec-Nietvoorbij to investigate the possibility of implementing deficit irrigation as a means to manage grapevine foliage.
The objective of the trial will be to evaluate the possibility of reducing growth vigour of vineyards, and thereby minimizing canopy management inputs and costs, by means of deficit irrigation as well as to determine the effect of these treatments on the irrigation water productivity (IWP).
1. To determine the effect that deficit irrigation has on canopy density and vegetative growth of non-manipulated grapevines compared to manipulated grapevines;
2. To determine the effect of different combinations of deficit irrigation strategies and canopy manipulations on the yield and wine quality;
3. To determine if reduced canopy management inputs are economically viable;
4. To determine the optimal balance between irrigation water application, yield, overall wine quality and canopy management costs;
5.To determine the effect of different irrigation strategies and canopy manipulations on the irrigation water productivity.