To identify the cumulative effect of winter drying on vine balance and wine quality.
Projections from climate change models indicate a warmer and drier future for most wine growing regions. Although there is less confidence in drying than warming, most climate models suggest a drier winter and spring. In regions where rainfall is greater than irrigation application (e.g. Barossa Valley, Great Western) the latter amount is usually less than 1.5 ML/ha (150 mm irrigation) during the growing season. Any long term decline in rainfall will necessitate increased irrigation from already limited water supplies.
The project will concentrate on vine activity during dormancy – specifically understanding root physiology and activity and how soil water deficits during dormancy impact overall vine balance and subsequent wine quality. Prior research has not explored these aspects and their correlation to soil water deficit or storage reserves. The experimental design and method incorporates five treatments within an experimental plot at the Nuriootpa Research Station, South Australia. All winter rainfall will be excluded from experimental plots (measurement row and adjacent ‘buffer’ rows) by using rain-out shelters.
Typical and reduced rainfall amounts within the shelters will be simulated using micro sprinklers. Treatment volumes and timing will be determined using winter rainfall deciles, calculated from existing climate information. The rain-out shelters will be removed at budburst and all treatment vines will receive the same level of irrigation during the subsequent growing season.
This project will assist grape growers to manage vine balance in dry winters in the current climate and prepare for future changes. A series of management strategies will be developed that growers will be able to rapidly implement during years of low winter/spring rainfall based on actual and projected winter rainfall probabilities.