Developing regression models between water use efficiency (WUE) and winter canola yield, under water and salinity stresses and different nitrogen fertilizer levels.

Due to increasing rate of consumption and focusing on decreasing the import rates of oily seeds, the producing of them have gained lots of emphasize in study region, in recent years. The Urmia Lake as one of the most important water bodies and tourism centers in Iran, is drying because of different reasons. The water scarcity in one hand, and the salinity amount addition in water and soil resources on the other hand, cause the agriculture sector to face severe challenges. The aim of this study is improving the regression relations between the seed yield and water use efficiency under water and salinity stresses and various N fertilizer levels. For this purpose, the experimental design in the form of completely randomized block design, in 3 replications, was conducted in the research field of the Water Engineering Department of Urmia University during 2012-13. The irrigation treatments were applied in 3 levels: irrigating up to the field capacity (FC), 75% of FC, and 50% of FC. The salinity stresses are also exerted in 3 levels with irrigation water: without salinity stress, 7 ds/m and 14 ds/m. The N fertilizer also was applied in 3 levels: 60,120 and 180 kg/ha. The results showed that increases the water and salinity stresses lead to the shrinkage in seed yield and WUE and more usage of N fertilizer leads to more amounts of WUE. In addition, applying the fertilizer can partly offset the reducing effects of salinity, while the irrigation is up to the FC level.