Water deficit is a major factor influencing yield and Canola seed oil content. A two years field
experiment was conducted during 2005 and 2006 growing seasons in the Agriculture Research Station of Torogh, Mashhad to evaluate response of Canola cultivars to limited water. Experimental design was a split plot with three replications in which irrigation regimes were allocated to main plots and cultivars to subplots. Irrigation treatments included 100 (R1), 80 (R2), 65 (R3) and 50 (R4) percent of water requirement based on previously determined water requirement of Canola in Mashhad. Cultivars were Zarfam, Okapi, SLM046 and Licord. The results showed that yield and yield components were significantly affected by drought stress in two years. In R3 seed yield was decreased at first year however, at R4 decreased seed yield was observed in both years. Water use efficiency in all stress treatments was higher than control. Average of WUE at all cultivars in control treatment was 2.78 g per kilogram by 3500 m3 watered requirement and 6.13 g per kilogram by 1750 m3 watered requirement in severe stress. The highest and lowest WUE observed in SLM046 in R4 and R1 treatments by 8.20 and 1.52 g per kilogram. These results showed considerable differences between
Canola cultivars regarding to WUE and yield analysis. In addition the ability of oil production by
canola cultivars under drought stress is not followed by seed yield. This ability to produce seed yield is so less than oil content.