Effect of Nitrogen Foliar Application and Different Levels of Irrigation on Yield of Canola in Gonabad, Iran

To study the effects of irrigation and nitrogen treatments on rapeseed(option 500 variety), an experiment was conducted at agricultural research station of Gonbad during 2003-2005.The station is located at 5 km east of Gonbad at an altitude of 45 meters above sea level and has Xerothermo Mediterranean climate.The experiment was carried out as factorial form in RCBD with 3 replications. Iirrigation treatments included the check (without irrigation), irrigation at flowering stage, and irrigation at flowering stage and seed filling stage. The nitrogen treatments consisted of the control (no N), applying N to the soil without foliar application, and applying N to the soil with foliar application. The foliar application of urea was applied in the beginning of stem elongation and flowering stages with 2.5 % concentration. The result of the first year of experiment showed that the effects of irrigation, nitrogen, and the interaction between the two variables were significant on grain yield. However, the effect of irrigation in the second year was not significant because of high rain fall. The two-year analysis showed that the effect of year was significant on grain yield, the number of secondary branches, and 1000 grain weight, reflecting that the climatic conditions varied in the two years of the experiment. Irrigation at flowering and seed filling stages together with N application to the soil and foliar application treatment had the highest yield (3426 kg/ha). Therefore, irrigation of canola is recommended for the seasons when there is not enough rain at flowering and seed filling stages.