Potential of Thermal Images and Simulation Models to Assess Water and Salt Stress: Application to Potato Crop in Central Tunisia

Abstract

The growing water scarcity is a real concern in Mediterranean countries characterized by semi-arid or arid climate such as Tunisia, where it is crucial to improve water use efficiency without affecting agricultural productivity. The importance of identifying methods and technologies to optimize water use in agriculture has been recognized worldwide, in response to the limited water availability. Objective of the paper was to verify the potential of the combined use of infrared thermography and simulation models to assess the effects of water and salt stress on potato crop parameters and crop yield, under the environmental conditions of central Tunisia. The database collected with field experiments allowed the application of Hydrus-2D model to simulate water and salt stress. The achieved results evidenced that water savings are possible in Tunisia if irrigation is scheduled based on the climate and/or plant water status. Experiments showed that the high variability on crop yield within the treatments was mainly associated to possible clogging phenomena, rather than emitters’ quality or deficiency in distribution uniformity. When considering the thermal image analysis, it was demonstrated that the crop water stress index (CWSI) is strongly related to soil matric potential, so that handled infrared thermography can be considered a powerful tool for irrigation scheduling of potato crop. Moreover, the rate of maximum evapotranspiration reduction estimated by model simulations, resulted fairly well correlated with the corresponding CWSI obtained by thermal images, thus evidencing the suitability of the model to assess the effects of water and saline stress on crop transpiration and to identify irrigation scheduling parameters aimed to optimize water use efficiency.