NON-CONTACTING TECHNIQUES FOR PLANT DROUGHT STRESS DETECTION

To insure high quality, high plant growth, drought stress detection is necessary for greenhouse operation. The goal of this study was to examine non-contacting techniques in plant drought stress detection. Non-contacting sensing techniques based on plant canopy temperature, plant leaf motion and plant water content were evaluated for drought stress detection using New Guinea Impatiens as a model plant. Threshold values of Crop Water Stress (CWSI), plant motion in the form of covariance of Top Project Canopy Area (TPCA), and Equivalent Water Thickness (EWT) were determined to identify the stress plants. The determined threshold values of CWSI and COVtpca agreed what was reported previously. The performance of the indicators were evaluated by comparing the timing of detection of the threshold values against the timing of human visual detection. The comparison showed that the CWSI was the most reliable indicator for early plant drought stress detection. The timing of the drought stress detection from the earliest to the latest are CWSI, EWT, and the plant motion based approaches.