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United States Department of Agriculture

Agricultural Research Service

Research Project: Management Strategies to Sustain Irrigated Agriculture with Limited Water Supplies

Location: Water Management Research

Title: Conventional and simplified canopy temperature indices predict water stress in sunflower

Authors
item Taghvaeian, Saleh -
item Comas, Louise
item DeJonge, Kendall
item Trout, Thomas

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 4, 2014
Publication Date: June 23, 2014
Citation: Taghvaeian, S., Comas, L.H., Dejonge, K.C., Trout, T.J. 2014. Conventional and simplified canopy temperature indices predict water stress in sunflower. Agricultural Water Management. 144:69-80.

Interpretive Summary: Two indicators based on remotely-sensed canopy temperature (one widely-used but requiring of complex input; the second, new with simplified input) were used in northern Colorado to monitor water stress in sunflower under six levels of regulated deficit irrigation. Both were sensitive to irrigation timing/depth and soil water deficit in the root zone, increasing as water availability decreased. Four crop parameters (light interception, Leaf Area Index, Leaf Water Potential, and root growth) documented crop stress and response to deficit irrigation treatments, and were also strongly correlated with both crop stress indicators in similar relationships. The results suggest that the new stress indicator, based solely on canopy temperature and estimated by a simple subtraction, may be used effectively in monitoring water stress and scheduling irrigations in deficit-irrigated sunflower.

Technical Abstract: Two indicators based on remotely-sensed canopy temperature were used in northern Colorado to monitor water stress in sunflower under six levels of regulated deficit irrigation. The two indicators included the widely-used Crop Water Stress Index (CWSI) and the new Degrees Above Non-stressed Canopy at Equal Stage (DANCES). In estimating CWSI, non-water-stressed baselines developed in this study were similar to those developed previously at another site in northern Colorado. Both CWSI and DANCES were sensitive to irrigation timing/depth and soil water deficit in the root zone, increasing as water availability decreased. Four studied crop parameters, namely the fraction of Intercepted Photosynthetically Active Radiation (fIPAR), Leaf Area Index (LAI), Leaf Water Potential, and root growth were all affected by deficit irrigation treatments, with the first three parameters decreasing and the last one increasing with decrease in water application. All of these crop parameters were also strongly correlated with CWSI and DANCES. Statistically significant relationships were developed to predict fIPAR, LAI, and relative root growth based on CWSI and DANCES, with coefficients of determination that were similar among the two temperature-based stress indicators. The results suggest that DANCES, based solely on canopy temperature and estimated by a simple subtraction, may be used effectively in monitoring water stress and scheduling irrigations in deficit-irrigated sunflower.

Last Modified: 12/22/2014
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