Krista Shellie* and Bradley King
*USDA-ARS, HCRL, 29603 U of I Lane, Parma, ID 83660 (krista.Shellie@ars.usda.gov)

In arid winegrape production regions, irrigation precision is limited by the logistical difficulty of monitoring vine water status. In previous research, we developed a model to predict the canopy temperature of a grapevine under well-watered conditions and used predicted and measured canopy temperatures to calculate a water stress index. The objective of this research was to automate data acquisition, calculation, and display of the index and to relate index values with irrigation events, soil moisture, and other indicators of vine water status. A sensor network system that included infrared radiometers, a weather station, soil moisture probe, tipping bucket rain gauge, and data logger was installed in commercial plots of Malbec and Chardonnay at different vineyard sites in southwestern Idaho. Data were acquired remotely in real time and a daily crop water stress index was calculated and displayed graphically on a web-based user interface that was accessible for use by vineyard managers. Daily water stress index values decreased after an irrigation event and increased between irrigation events. The depth of water penetration during an irrigation event differed by vineyard and corresponded with irrigation event duration. Values of midday leaf water potential corresponded with water stress index values; however, the water stress index was more responsive to irrigation events than leaf water potential. Results from the first year of this two-year field trial suggest that this methodology can provide a real-time, automated daily indicator of vine water status for use as a decision-support tool in a precision irrigation system.

Funding Support: Idaho State Department of Agriculture Specialty Crop Block Grant, U.S. Dept. of Agriculture, Agricultural Research Service