Understanding the effect of water stress on yield and its components is the essential step in developing of high yielding and stable genotypes. Substantial reduction in grain yield can be caused by water deficit depending on the intensity, duration and the developmental stage at which water stress occurred. An experiment was conducted in the lathouse at Sinana Agricultural Research Center in 2006/2007 to evaluate the effect of water deficit on grain yield and yield components of eighteen durum wheat genotypes induced at different growth stages. Grain yield and other agronomic traits of all genotypes were significantly reduced and the reduction was much more pronounced under stress induced from tillering to crop maturity. Grain yield per plant was reduced by 72, 37 and 17.1% due to stress induced at tillering, flowering and grain-filling stages as compared to the well-watered treatment, respectively. Kilinto and Gerardo were found to be stable and drought tolerant genotypes whereas S-17B and Boohai were highly susceptible. The most drought tolerant genotypes were found to maintain relatively high levels of kernel numbers per spike and hundred-kernel weight. Mean kernel weight was associated to the duration of grain filling and grain filling rates and these traits contributed to a greater yield under water stress conditions.

Key words: Durum wheat, water deficit, yield components.