Submitted to: Plant Biosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2012
Publication Date: 1/3/2013
Citation: Baker, J.T., Mahan, J.R., Gitz, D.C., Lascano, R.J., Ephrath, J.E. 2013. Comparison of deficit irrigation scheduling methods that use canopy temperature measurements. Plant Biosystems. 147(1):40-49.
Technical Abstract: Canopy temperature provides an easy-to-acquire indication of crop water deficit that has been used in irrigation scheduling systems, but interpretation of this measurement has proven difficult. We compared the timing of irrigation application of the Stress Time (ST) method of irrigation scheduling with the Stress Degree Hours (SDH) method on deficit irrigated cotton (Gossypium hirsutum L.) where each irrigation event delivered 5 mm of water through subsurface drip tape. A well-watered control and a dry land treatment were also part of the experimental design. We used data collected from the well watered and dry land treatments to develop upper and lower baselines for the Crop Water Stress Index (CWSI) appropriate for cotton grown at our location. The ST method detected drought stress earlier in the growing season when both the SDH and CWSI indicated very little drought stress. The SDH method resulted in the application of irrigations relatively later in the growing season when the CWSI also detected higher levels of drought stress. These results suggest that the adding certain micrometeorological variables to simple canopy temperature methods of deficit irrigation scheduling may improve the ability to detect and quantify the degree of crop drought stress.