ASABE Technical Library - Abstract

Abstract. Leaf temperature measurement using infra-red thermometry has been used to predict plant water stress empirically. However, to develop robust indices like crop water stress index (CWSI) usually it is recommended to measure canopy temperature of saturated (unstressed), stressed, and current plant water status of the tree under observation at the same time, which is not practical to obtain. This study proposes a novel method to develop a stress index by measuring leaf temperature continuously. An inexpensive, easy to use sensing system was developed to predict plant water status for tree crops by measuring leaf temperature and microclimatic variables in the vicinity of a leaf continuously. The system was installed on a tree to continuously monitor the leaf by logging leaf temperature, air temperature, relative humidity, wind speed and PAR (Photosynthetically Active Radiation). Data collected from preliminary field experiments was used to calculate crop water stress index (CWSI) which was independent of light and wind conditions. This sensing system shows great potential to be used as irrigation scheduling tool as it was able to provide daily CWSI value which follows similar pattern like of actual plant water stress index.