Water stress monitoring in olive trees using thermal imaging

In order to decrease water consumption in agricultural sector, deficit irrigation has been suggested. For preventing a heavy loss in crop yield, management of water stress is essential. Common methods for measuring plant water stress such as stomatal conductance are time-consuming and require specialized labor and a large number of measurement. Temperature of leaf or canopy surface can be an indicator of stomatal conductance or plant water stress. Canopy temperature is not only affected by stomatal conductance, but also with environmental conditions such as air temperature or vapor pressure deficit. Crop water stress index (CWSI) is recently proposed to solve these problems. By comparing the canopy temperature with two reference temperatures in crop water stress index, the effect of environmental conditions can be minimized. Thermography is a non-contact approach toward surface temperature measurement without interfering with plant activities. The general goal of this study was to obtain CWSI using thermal images and to evaluate the potential of this method for predicting the stomatal conductance. In order to achieve this goal, thermal images from olive trees under five deficit irrigation treatments with three replications were obtained. The results showed a significant (R2ADJ = 0.83) relationship between CWSI and the stomatal conductance