Effect of Irrigation Regime on Water and Nitrogen Use Efficiency in Sunflower at Various Levels of N-Application and Plant Density Under Urmia Climate Conditions

This research was conducted to study the effects of water deficit stress، nitrogen application rates، and Planting density on economic and biologic water use efficiency and nitrogen use efficiency of oily sunflower at Agricultural Research Center of West-Azerbaijan during 2007-2008. The study consisted of split-split-plot experiments using randomized complete block design with 3 replications. The main factor consisted of irrigation treatment including optimum irrigation، moderate stress and severe stress where irrigation was done after depletion of 50%، 70% and 90% of field capacity، respectively. Three nitrogen levels consisting of 00، 60 and 220 Kg N ha- were considered as sub plots and sub – sub plots consisted of three density of 5. 55، 6. 66 and 8. 33 plant m-2. Severe drought stress reduced the grain yield by 44% compared to the optimum irrigation condition. Grain yield increased with nitrogen application rate. Reducing irrigation intervals improved economical and biological water use efficiencies. Increasing nitrogen application rate improved economical and biological water use efficiencies mainly due to increased grain and biological yields. By increasing nitrogen consumption from 00 to 220 kg/ha، nitrogen use efficiency declined 8/89 kg/ha. Results of this study indicated that nitrogen application rate and density for improving nitrogen and water use efficiency should be adjusted accordingly with the availability of water in the soil.