The effect of different amounts of Nitrogen fertilizer and sowing date on phenological traits, seed and yield components of canola (Brassica napus L.)

In order to determine the effect of different amount of nitrogen application in different sowing dates on phenological traits, plant height and seed yield of canola (Brassica napus L.) Hyola 401 cultivar, the experiment was conducted as a randomized complete block design in a split-plot four times in Biekola Agriculture Research Station in Neka city during 2008-2009. Five sowing dates including 29 October, 8, 18, 28 November and 8 December were considered as main plots and four levels of nitrogen urea fertilizer application including 150, 200, 250 and 300 kg/ha urea were considered as sub plots. The results revealed the significance of sowing date and nitrogen for number of days to flowering, number of days to end of flowering, plant height, number of pods per main raceme, number of pods per plant, number of seeds per pod, 1000 seed weight and Seed yield Also the nitrogen effect was significant on each studied traits except duration of flowering. Interaction sowing date and nitrogen application were not significant for more studied traits exept number of pods per plant and 1000-seed weight. Among yield components, number of pods per main raceme and pods per plant had significant correlation with seed yield, indicating variations of these traits in different sowing dates, and also more effect of different nitrogen levels on seed yield. The significant positive correlation was observed between seed yield and each phenological trait, indicating the first and second sowing dates and also high amount of nitrogen levels made increasing amount of phenological traits and seed yield. In the first sowing date the seed yield related to four nitrogen application levels were 2864, 3026, 3276 and 3707 kg/ha respectively. For the fifth sowing date seed yield were 1754, 1835, 1973 and 2268 kg/ha respectively. Therefore one of the effective ways for compensating of decreasing yield components and seed yield due to late planting date is increasing the amount of nitrogen application.