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

The crop water stress index (CWSI) is a valuable tool for monitoring and qu antifying water stress as well as for irrigation scheduling. This study was conducted during the 1990 and 1991 growing seasons at the Colorado State U niversity Horticulture Farm near Fort Collins, CO, USA (40 35'N latitude, 1 05 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 wat er status and irrigation scheduling of wheat. The difference in crop canopy to air temperature (T-c-T-a), measured above a crop was negatively related to the atmospheric vapor pressure deficiency (AVPD) [R-2=0.88 and p=0.0001 ]. However, this relationship between (T-c-T-a) and AVPD can be used to dev elop a non stressed baseline equation and consequently the crop water stres s index (CWSI). By using non-water-stressed baseline on data collected freq uently through the growing season, CWSI values may provide a valuable tool for monitoring water status and planning irrigation scheduling for wheat an d which is extendable to other similar agricultural crops. (C) 2001 Elsevie r Science B.V. All rights reserved.