عنوان مقاله [English]
Canola is an oilseed crop that is getting more attention as a source of vegetable oil in our country. Canola requires high rates of nitrogen and is regarded as a nitrogen-demanding crop. In order to study the effects of different rates of nitrogen on yield and seed quality of winter rapeseed Var. SLM046 and its potassium & phosphorus uptake an experiment was conducted in Zanjan Agricultural Research Center in 2001. The experiment was carried out in three replications using a factorial experiment in randomized complete block design. Five rates of N(0, 60, 120, 180 and 240 kg/ha) from four different sources (Sulfur coated urea, Urea, Ammonium nitrate and Ammonium sulphate, were used in this experiment. The effect of nitrogen on the canola yield components can be seen in the increased number of the seedpods per plant, which is the main factor in improving the yield of canola seeds. The level of glucose inolate in canola is considered as an important canola quality index, which seems to be affected by the level of nitrogen supplements. The highest seed yield was obtained from the application of 240 kg N/ha, the highest oil content in the seeds was obtained with applications of 120 kg N/ha and the highest oil yield was also obtained with highest level of nitrogen, so it shows that rapeseed has high nitrogen requirment. The canola seed meals content of glucose inolate decreased significantly with increasing nitrogenrates. The largest number of seedpods per plant was obtained with 240kg N/ha. The highest protein content (19/6%) was obtaind from highest level of nitrogen. Most accumulation of phosphorus in the leaves of plant was occurred in 60 kg N/ha and it decreased significantly with increasing nitrogen.Potassium uptake increased with increasing nitrogen rates. There was a great correlation between oil yield and grain yield (r=0/99**). According to these results, selection of fertilizers and level of nitrogen should be evaluated by oil yield character.