Evaluation of different approaches for estimating and mapping crop water status in cotton with thermal imaging
Canopy temperature has long been recognized as an indicator of plant water status, therefore, a high-resolution thermal imaging system was used to map crop water status. Potential approaches for estimating crop water status from digital infrared images of the canopy were evaluated. The effect of time of day on leaf temperature measurements was studied: midday was found to be the optimal time for thermal image acquisition. Comparison between theoretical and empirical approaches for estimating leaf water potential showed that empirical temperature baselines were better than those obtained from energy balance equations. Finally, the effects of angle of view and spatial resolution of the thermal images were evaluated: water status was mapped by using angular thermal images. In spite of the different viewing angles and spatial resolution, the map provided a good representation of the measured leaf water potential.
KeywordsCotton Leaf water potential Site-specific irrigation Water stress CWSI Infrared thermography Canopy temperature Remote sensing
This research was supported by Research Grant no. TB-8006-04 from BARD, the United States—Israel Bi-national Agricultural Research and Development Fund, and Grant 458-0361-04 from the Chief Scientist of the Israel Ministry of Agriculture and Rural Development. Also, we would like to thank Mr. R. Brikman and Dr. A. Bosak for their help in conducting the field measurements and image acquisition. This paper is contribution no 70408 from the ARO, Volcani Center, Bet Dagan 50250, Israel.
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