ARS | Publication request: Canopy temperature view angle affects on the water deficit index

Submitted to: ASABE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 26, 2006
Publication Date: July 9, 2006
Citation: Bausch, W.C. 2006. Canopy temperature view angle affects on the water deficit index. ASABE Annual International Meeting. Portland Oregon, July 9-12, 2006

Technical Abstract: Increased water use efficiency for irrigated agricultural crop production requires solutions that improve irrigation scheduling and management. Several techniques exist that utilize canopy temperature measurements to assess the severity of plant water stress. The Water Deficit Index (WDI) was developed to evaluate the plant water status for both full and partially vegetated sites from nadir view canopy temperature measurements. However, the WDI as defined is not strictly related to plant water stress. Nonwater stressed vegetation with a dry soil surface may result in a WDI greater than zero which indicates that plant transpiration rates are below atmospheric potential. The objective of this study was to evaluate whether or not canopy temperature measured from an oblique view versus the nadir view would improve the WDI for early season use in irrigated corn. Five drip irrigated corn plots (12 m wide x 15 m long) were utilized in this study; one was well irrigated throughout the growing season and the other four were subjected to plant water stress at various plant growth stages. An additional plot was maintained as bare soil for bare soil related measurements. Vegetation cover, canopy temperature, air temperature, and canopy reflectance measurements were collected throughout the growing season.