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Research Project: Improving the Quality of Grapes, Other Fruits, and their Products through Agricultural Management

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Title: Can a canopy temperature-based stress index enhance water use efficiency in irrigated wine grape under arid conditions?

item Shellie, Krista
item King, Bradley - Brad

Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2016
Publication Date: 6/27/2016
Citation: Shellie, K., King, B.A. 2016. Can a canopy temperature-based stress index enhance water use efficiency in irrigated wine grape under arid conditions?. American Society of Enology and Viticulture Annual Meeting Abstracts. 67th ASEV Technical Abstracts/ pg. 69.

Interpretive Summary:

Technical Abstract: Enhancement of irrigation water use efficiency and water productivity in arid wine grape production regions is hindered by a lack of automated, real-time methods for monitoring and interpreting vine water status. A normalized, water stress index calculated from real-time vine canopy temperature measurements has been shown in wine grape to correspond well with irrigation amounts and events under arid conditions; however, little is understood about how to interpret water stress index values and the relationship of index values with other commonly used indicators of vine water status. The objective of this study was to relate canopy temperature-based water stress index values for the wine grape cultivars Syrah and Malbec with seasonal measurements of water productivity and carbon isotope composition and to compare daily index values with daily measurements of midday leaf water potential, leaf gas exchange and leaf chlorophyll fluorescence. Own-rooted vines of each cultivar were grown in replicated plots under arid conditions in an experimental vineyard in Parma, ID and supplied, over two growing seasons, with either 35 or 70% of their estimated water demand. The daily water stress index decreased rapidly in response to irrigation events and the amounts of decrease corresponded with the amounts of irrigation. In both cultivars, vines irrigated at 35% had higher water stress index values, higher water productivity, and less negative 13C/12C in the sugar of mature berries than vines irrigated at 70%. The relationship between the daily stress index and midday leaf water potential was stronger for Syrah than for Malbec. Findings from this study facilitate interpretation of normalized, water stress index values and show that canopy temperature is a sensitive indicator of vine water status. Measurement of canopy temperature and calculation of the water stress index is amenable to automation for use as a decision-support tool in a precision irrigation system.