The effect of planting date and nitrogen rate on agronomical traits of spring canola cultivar

摘要

This paper emphasizes the importance of rapeseed (Brassica napus L.) to become an alternate oilseed crop in Karaj, Iran during 2007 and 2008. Four planting dates were established at about 10 day intervals from mid March to late April (21 Mar, 31 Mar, 11 Apr, and 20 Apr 2007; and 31 Mar, 11 Apr, 20 Apr, and 29 Apr 2008). Four N fertilizer rates were established (0, 60, 140, and 220 kg/ha). In both years, there were effects on plant growth, yield, and yield components due to planting dates, nitrogen rates and cultivars. Cultivars tended to respond similarly to planting date and nitrogen rate for seed yield in both years of the study. From this study, it appeared that seeding rapeseed from 31 Mar to 11 Apr gives a greater assurance for higher yields. The present results highlight the practical importance of adequate N fertilization in yield formation in summer oilseed rape and suggest that the rate of 140 N kg/ha is adequate for the crop to meet its N requirements.