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Non-contacting techniques for detecting plant drought stress in a closed environment

Yang, Yang
http://rave.ohiolink.edu/etdc/view?acc_num=osu1068499233

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Food, Agricultural, and Biological Engineering.
Plant drought stress refers to the condition in which plant cells and tissues are at less than full turgor. When drought stress occurs, almost all the processes associated with plant growth are affected. To insure high quality, high plant growth, drought stress detection is necessary for greenhouse. The goal of this study was to examine non-contacting techniques in plant drought stress detection. Efforts were centered on confirming the previous findings using infrared-thermalcouples (IRT) and imaging techniques, and the development and evaluation of a model based multi-spectral technique in drought stress detection for New Guinea Impatiens plants grown in a controlled environment. To validate previous study reports on using IRT and imaging techniques in drought stress detection, experiments were conducted in a growth chamber. Infrared thermometry was applied to measure the plant canopy temperatures during the experiments. The crop water stress index (CWSI) values of the plants were calculated from the measured plant canopy temperatures, the air temperature, the vapor pressure deficit (VPD) of the air, and other environmental conditions. Plants' top projected canopy area (TPCA) images were acquired using a machine vision system. The motion of the plants was extracted from the TPCA images. The indicators used to describe the motion of the plants were the covariance of the TPCA (COVtpca) and the instant relative canopy motion (IRCM). Plant canopy multispectral reflectance was measured using a spectroradiometer system. The average equivalent water thickness (EWT) of the plants was calculated from the measured canopy reflectance, using an established procedure based on model inversion techniques. The canopy temperatures of the stress plants were found to be 1-2 0C higher than the air temperature, and to be consistently higher than the canopy temperature of the control plants. The threshold values of CWSI were established, using the CWSI values of the control plants. The performance of this indicator was evaluated by comparing the timing of detection of the threshold values against the timing of human visual detection. It was confirmed that the CWSI threshold values could detect the drought stress earlier than the human visual detection in most of the cases. The threshold values of the COVtpca and IRCM were also determined. It was confirmed that the plant motion-based indicators could detect the plant drought stress no latter than human visual observation. The studies on multispectral reflectance of the plants on both the leaf and canopy scales indicated that the multispectral technique was able to differentiate plants at different water status. The threshold values of the EWT determined were found effective in detecting the plant drought stress. Most EWT based detections were earlier than visual detection most of the times. Comparison among performances of the above indicators showed that the CWSI was the best indicator in 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.
Peter Ling (Advisor)
265 p.
Multi-spectral reflectance; Leaf water status; New Guinea Impatiens; Controlled environment plant production; Leaf reflectance modeling; PROSPECT+SAIL model; Evaportranspiration; Equivalent water thickness; Plant sensing; Drought stress; Remote sensing

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Citations

  • Yang, Y. (2003). Non-contacting techniques for detecting plant drought stress in a closed environment [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1068499233

    APA Style (7th edition)

  • Yang, Yang. Non-contacting techniques for detecting plant drought stress in a closed environment. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1068499233.

    MLA Style (8th edition)

  • Yang, Yang. "Non-contacting techniques for detecting plant drought stress in a closed environment." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1068499233

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.