A tool for detecting crop water status using airborne high-resolution thermal imagery

摘要

Knowledge on crop water status at the orchard scale is necessary for the efficient management of irrigation water. Canopy temperature has long been recognized as a plant water status indicator, and crop water stress index (CWSI), which is obtained from canopy temperature could be used as a tool for remotely detecting plant water status from airborne high-resolution thermal imagery. In 2012, CWSI baselines for olive and peach trees were derived from infrared thermometer data. An aircraft equipped with a thermal sensor flew over two orchards acquiring high-resolution thermal images. At the same time, leaf water potential (Ψ_L) was measured in eighteen trees per specie. Relationship between the difference of canopy and air temperature (T_c-T_a) and Ψ_L had a R~2 of 0.74 and 0.82, for peach and olive, respectively. CWSI ranged from zero to one and showed a significant correlation with Ψ_L. Maps of estimated Ψ_L (derived from CWSI -Ψ_L relationships) were able to detect the spatial variability of plant water status within the orchards, and may be a feasible tool for irrigation purposes.