Optimising the recovery of vine performance following irrigation during extended periods of water deficit
Abstract
The project reported here was undertaken in a commercial Shiraz vineyard in the Great Southern wine region of WA. Production in this region is predominantly rain-fed with less than 1 ML/ha supplementary irrigation input. In such systems with limited irrigation water availability, irrigation is necessarily applied at low volumes and infrequently – i.e., vines can become water stressed for extended periods of water deficits.
Summary
In predominantly rain-fed viticultural systems located in relatively low rainfall regions, water deficit is an ever present limitation to productivity. As the water available for supplemental irrigation is low, irrigation is used strategically for avoiding excessive vine stress while also supporting and ripening an economic crop. When available water for irrigation is limited, applications necessarily occur infrequently, or at low volumes or both. Any of these regimens poses a risk that vines may at times experience extended spells of water deficits that severely limit vine functioning. The severity can vary spatially within a vineyard block (e.g. as a function of soil depth/topography) and temporally (e.g. periods of high versus low evaporative demand). The effects on vine functioning can also be compounded when periods of soil water deficit coincide with other stressful conditions such as high temperatures, high photon flux densities, and a dry atmosphere.
This project examined spatial variation in water deficits using d13C from winter bud samples and berry soluble solids at harvest. Leaf physiological functioning during extended periods of stress as well as recovery following small volume irrigation applications were monitored in different vine vigour zones. Spatial variations in irrigation water utilisation, as well as productivity of applied water were also examined. Furthermore, the site served as one of the nodes of another Wine Australia Soil and Water Initiative project (Goodwin et al., DPI 04/04), which assessed wine quality attributes from different vigour zones.