Water use efficiency of winter wheat under deficit irrigation

Abstract

The relationships between crop yield and water applied such as water use efficiency and water production function are necessary for application in planning, design and management of irrigation schemes. This study was conducted to determine Water Use Efficiency (WUE) of wheat obtained from irrigation cutting off after stem elongation (IC1), flowering (IC2), dough (IC3) stages and full irrigation (IC4) with treatments of 1.00 (I1), 0.75 (I2) and 0.50 (I3) for ratio of water amount (IW) to Cumulative Pan Evaporation (CPE) for two winter varieties. Results revealed that with increasing irrigation events from two to five, the WUE decreased. Generally, average WUE varied from 0.581 to 1.894 kg m-3. The WUE of two wheat varieties were nearly identical. Applying IC4 to IC1 as well as I1 to I3 treatments caused an increasing pattern in the WUE. The WUE from IC1, IC2 and IC3 were increased about 58.3, 56.9 and 31.2% relative to that of IC4 with average of 0.923 kg m-3, respectively. The WUE from I2 and I3 were increased about 20.6 and 43.6% comparative to that of 11 with average of 1.04 kg m-3, respectively. Using grain yield and other independent variables measured during two cropping years, several water production functions were worked out so that more than 93% of the variability in the achieved grain yield can be explained by water applied, levels of irrigation cutting off during wheat growth stage and wheat varieties. The comparison of grain yield from developed model with measured values revealed a satisfactory agreement between them. © 2007 Asian Network for Scientific Information.