ARS | Publication request: Non-contacting techniques for plant drought stress detection

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2008
Publication Date: N/A

Interpretive Summary: Water is necessary for plant growth and development, but is a limited, and sometimes expensive, resource. Substantial increases in yield could be possible if irrigation water was applied at the most appropriate time to prevent excessive drought stress. With the increase in the cost of energy required to pump and move water to desired locations, coupled with the decrease of available water for irrigation, it is essential to attain the maximum benefit from each unit quantity of water used for irrigation. Plant drought stress detection is thus of great importance. Human visual assessment of crop drought stress is qualitative at best, with the terms "good" or "poor" frequently used to describe crop condition. We studied the performance of different sensing techniques that, not only could detect the early symptoms of crop water stress but, also were able to quantitatively describe plant water status. The study indicates that electronic techniques in infrared sensing, imaging etc. can all be applied in crop water status assessment and drought stress detection. The different sensing techniques evaluated in this study can provide improved tools to agricultural managers to assess crop water status more reliably in a quantitative manner and to manage irrigation more efficiently.

Technical Abstract: Non-contacting sensing techniques based on plant canopy temperature, plant leaf motion, and plant canopy reflectance were evaluated for drought stress detection using New Guinea Impatiens as a model plant. The performances of Crop Water Stress Index (CWSI), plant motion in the form of Covariance of Top Project Canopy Area (COVTPCA), leaf water content represented as Equivalent Water Thickness (EWT) in detect drought stress detection were studied. The evaluation was conducted by comparing the timing of detection of the drought stress against the timing of the incipient drought stress defined by measured evaportranspiration (ET) and 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 is CWSI, EWT, and the plant motion based approaches.