Establishing crop water stress index (CWSI) threshold values for early and non-contact detection of plant water stress

Early, non-contact, non-destructive, and quantitative detection of plant water stress with the application of infrared thermometry using a crop water stress index (CWSI) was established. A CWSI model for plants grown under controlled environments was developed using thermodynamic principles and energy balance of the plant. CWSI threshold values were established with a parametric approach. The effectiveness of the sensing technique was evaluated using timing of the stress detection by a grower. The CWSI-based technique was able to detect the stress one to two days prior to the time of stress detection by visual observation. Overall results of this study suggested that pre-visual and non-contact detection of plant water stress with infrared thermometry application using CWSI is feasible.