A SOIL-PLANT-ATMOSPHERE APPROACH TO EVALUATE THE EFFECT OF IRRIGATION/FERTIGATION STRATEGY ON GRAPEVINE WATER AND NUTRIENT UPTAKE, GRAPE QUALITY AND YIELD

Abstract

Water is a scarce resource worldwide and a particular problem for producers of wine grapes in Australia, where drought occurrences are frequent, determining severe limitations to vine growth and productivity. Consequently, most vineyards are irrigated and the development of efficient water and nutrient management and monitoring practices are required. This research presents preliminary results of the application of a soil-plant-atmosphere approach to accurately assess vine water and nutrient uptake on grapevines (Vitis vinifera L. var. Shiraz) located in Richmond New South Wales (NSW) (season 2004-05). Soil water and nutrient monitoring (measured as volumetric soil moisture and soil electric conductivity changes, respectively) was carried out by using the newly developed TriSCAN® probes (Sentek Pty. Ltd., Australia). The TriSCAN®probes were distributed in a 3D array close to the root-zone to create 3D animations of soil wetting patterns and nutrient patterns of fully irrigated (FI) and regulated deficit irrigation (RDI) treatments. Soil water and nutrient dynamics were studied in post-harvest for this paper in a period of 17 days. Animations of soil moisture and nutrient patterns were obtained using the WPA copyright software. Through animation analysis, it was found that the zones of maximum root water and nutrient uptake occurred initially near the vine trunk and then progressed to deeper layers of the active root-zone. Whole vine transpiration rates were measured using sap flow probes (compensated heat-pulse) and plant water status was measured as midday stem water potential (ψs) for irrigation scheduling purposes. Weather data were collected from a meteorological station close to the trial site. For the studied season, only mild vine water stress was achieved in RDI treatments (ψs values between -0.8 to -1.1 MPa), therefore, no significant differences were found in grape quality and yield between fully irrigated and RDI vines. However, significant reduction in water application was achieved in RDI compared with fully irrigated vines (36% less). A soil-plant-atmosphere assessment throughout the whole season allows accurate irrigation/fertigation practices minimising fertiliser leaching losses, therefore reducing the negative environmental impacts of irrigation.