Scheduling Single Irrigation for Rainfed Wheat Using Crop Water Stress Index (Case study: the upper part of the Karkheh basin)

This study was conducted to study scheduling of single irrigation for rain-fed wheat using crop water stress index (CWSI) for arid and semiarid regions of Honam plain located in upstream of Karkheh River Basin of Iran during 2004-2005. Three cultivated rain-fed wheat were selected to conduct the treatments. Each farm separated to 2 part: (1) rain-fed (2) single irrigation in spring by depth of 60 cm. Application of single irrigation was different in 3 farms which were in heading, flowering, and milk stages accordingly. Soil water content in 60 cm soil depth and canopy temperature in flowering and milk development stages was measured in different times. CWSI was evaluated when upper and lower base line for non-transpiring were determined. Lower and upper baseline for non-transpiring was Tc –Ta = -2.089 VPD 2.28 and 6.2oC accordingly and CWSI and canopy temperature was 0.36 and 26.4. CWSI and yield variation were in 83% agreement. Moreover, wheat canopy temperature and soil water content showed a high agreement (R2) of 0.78.