Use of crop water stress index for monitoring water status and scheduling irrigation in wheat

Ali Abdullah Alderfasi, , a and David C. Nielsenb

a Department of Plant Production, College of Agriculture, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia 


b USDA-ARS, Central Great Plains, Akron, OH 80720, USA
Accepted 13 March 2000. Available online 13 February 2001.


The crop water stress index (CWSI) is a valuable tool for monitoring and quantifying water stress as well as for irrigation scheduling. This study was conducted during the 1990 and 1991 growing seasons at the Colorado State University Horticulture Farm near Fort Collins, CO, USA (40°35′N latitude, 105°05′W longitude and 1524 m elevation). The main objective was to develop a baseline equation, which can be used to calculate CWSI for monitoring water status and irrigation scheduling of wheat. The difference in crop canopy to air temperature (TcTa), measured above a crop was negatively related to the atmospheric vapor pressure deficiency (AVPD) [R2=0.88 and p=0.0001]. However, this relationship between (TcTa) and AVPD can be used to develop a non-stressed baseline equation and consequently the crop water stress index (CWSI). By using non-water-stressed baseline on data collected frequently through the growing season, CWSI values may provide a valuable tool for monitoring water status and planning irrigation scheduling for wheat and which is extendable to other similar agricultural crops