Crop Water Stress Index of an irrigated vineyard in the Central Valley of California

Authors: Prueger, John; PARRY, CHRISTOPHER - Pioneer Hi-Bred Seed Company; Kustas, William - Bill; Alfieri, Joseph; ALSINA, MARIA - E & J Gallo Winery; NIETO, HECTOR - Institute Of Agrifood Research And Technology; Wilson, Tiffany; HIPPS, LAWRENCE - Utah State University; Anderson, Martha; Hatfield, Jerry; GAO, FEN - Orise Fellow; McKee, Lynn; McElrone, Andrew; AGAM, NURIT - Ben Gurion University Of Negev; LOS, SEBASTIAN - Utah State University

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2018
Publication Date: 10/23/2018
Citation: Prueger, J.H., Parry, C.K., Kustas, W.P., Alfieri, J.G., Alsina, M.A., Nieto, H., Wilson, T.G., Hipps, L.E., Anderson, M.C., Hatfield, J.L., Gao, F., McKee, L.G., McElrone, A.J., Agam, N., Los, S. 2018. Crop Water Stress Index of an irrigated vineyard in the Central Valley of California. Irrigation Science. 37(3):297–313. https://doi.org/10.1007/s00271-018-0598-4.
DOI: https://doi.org/10.1007/s00271-018-0598-4

Interpretive Summary: Many California vineyards are faced with water-limiting conditions caused by repeated drought cycles. Irrigation management strategies for vineyards are important to prevent water waste through over irrigation and to ensure that the right amounts of water are applied to maintain vine production and high quality grapes. Estimating the right amounts of irrigation for vineyards requires information on soil water content, local meteorological conditions and vine canopy temperatures. A long-term study is ongoing in several California vineyards to assess daily evapotranspiration rates from vast tracts of vineyards. This information can be used determine optimal times and rates of irrigation to the vines. To avoid water stress to the vines from too little irrigation a crop water stress index (CWSI) is computed from measurements of leaf/canopy temperatures and local meteorological conditions. The CWSI can be used as an early warning system against water stress in a vineyard. This can aid increasing irrigation efficiency (less water) without causing yield reduction due to lack of water.

Technical Abstract: Water-limiting conditions in many California vineyards necessitate assessment of vine water stress to aid irrigation management strategies and decisions. This study was designed to evaluate the utility of a crop water stress index (CWSI) using multiple canopy temperature sensors and to study diurnal signature in the stress index in an irrigated vineyard. A detailed instrumentation package comprised of eddy covariance instrumentation, ancillary surface energy balance components, soil water content sensors and a unique multi-canopy temperature sensor array were deployed in a production vineyard near Lodi, CA. The instrument package was designed to measure and monitor hourly growing season turbulent fluxes of heat and water vapor, radiation, air temperature, soil water content directly beneath a vine canopy, and vine canopy temperatures. April 30–May 02, June 10-12 and July 27-28, 2016 were selected for analysis as these periods represented key vine growth and production phases. Considerable variation in computed CWSI was observed between each of the hourly average individual canopy temperature sensors throughout the study; however, the diurnal trends remained similar: highest CWSI values in morning and lowest in the late afternoon. While meteorological conditions were favorable for plant stress to develop, soil water content near field capacity due to frequent irrigation allowed high evapotranspiration rates resulting in downward trending CWSI values during peak evaporative demand. While the CWSI is typically used to evaluate plant stress under the conditions of our study, the trend of the CWSI suggested a lowering of plant water stress as long as there was adequate soil water available to meet atmospheric demand.