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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #309521
Title: Comparison of canopy temperature-based water stress indices for maize

Author
item DeJonge, Kendall
item TAGHVAEIAN, SALEH - Oklahoma State University
item Trout, Thomas
item Comas, Louise

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2015
Publication Date: 4/18/2015
Publication URL: http://handle.nal.usda.gov/10113/60703
Citation: DeJonge, K.C., Taghvaeian, S., Trout, T.J., Comas, L.H. 2015. Comparison of canopy temperature-based water stress indices for maize. Agricultural Water Management. 156 (2015) 51-62.

Interpretive Summary: In this maize experiment, six treatments of regulated deficit irrigation levels were evaluated in terms of canopy temperature in the form of six stress indices (three previously proposed and three introduced in this study) used to quantify water stress. Canopy temperature was highly correlated with leaf water potential (R2 = 0.895). To avoid potential bias from soil texture, the lowest observation from the non-stressed treatment was chosen as the baseline for DANS and IDANS indices. Canopy temperatures and stress indices were responsive to evapotranspiration-based irrigation treatments. DANS and DACT were highly correlated with CWSI above the corn threshold 28 °C used in the TTT method, and all indices showed linear relationship with soil water deficit at high temperatures.

Technical Abstract: Infrared thermal radiometers (IRTs) are an affordable tool for researchers to monitor canopy temperature. In this maize experiment, six treatments of regulated deficit irrigation levels were evaluated. The main objective was to evaluate these six treatments in terms of six indices (three previously proposed and three introduced in this study) used to quantify water stress. Three are point-in-time indices where one daily reading is assumed representative of the day (Crop Water Stress Index - CWSI, Degrees Above Non-Stressed - DANS, Degrees Above Canopy Threshold - DACT) and three integrate the cumulative impact of water stress over time (Time Temperature Threshold - TTT, Integrated Degrees Above Non-Stressed - IDANS, Integrated Degrees Above Canopy Threshold - IDACT). Canopy temperature was highly correlated with leaf water potential (R2 = 0.895). To avoid potential bias, the lowest observation from the non-stressed treatment was chosen as the baseline for DANS and IDANS indices. Early afternoon temperatures showed the most divergence and thus this is the ideal time to obtain spot index values. Canopy temperatures and stress indices were responsive to evapotranspiration-based irrigation treatments. DANS and DACT were highly correlated with CWSI above the corn threshold 28 °C used in the TTT method, and all indices showed linear relationship with soil water deficit at high temperatures. Recommendations are given to consider soils with high water-holding capacity when choosing a site for non-stressed reference crops used in the DANS method. The DACT may be the most convenient index, as all it requires is a single canopy temperature measurement yet has strong relationships with other indices and crop water measurements.