The Effects of Nitrogen Fertilizer Forms Applied at Different Growing Periods on Yield and Yield Components of Winter Rapeseed (Brassica napus ssp. oleifera L.)

This research was conducted to investigate the effects of nitrogen fertilizer forms applied at different growing stages (rosette, jointing stage, pre-flowering and post-flowering) on yield and yield components of winter rapeseed. In the study, winter rapeseed cultivar Orkan and ammonium sulphate (26% N), ammonium nitrate (33% N) and urea (44% N) were used as material. Plant height, number of lateral branches, number of capsule in main branch, one thousand seed weight, seed yield and oil ratio were determined in the study. The results revealed that nitrogen fertilizer forms and fertilizer application stages significantly affected the investigated traits. The highest seed yield would be obtained if ammonium sulphate in rosette stage, urea in jointing stage and ammonium nitrate in pre-flowering stage were applied. However, urea should be advised to increase seed yield of rapeseed if nitrogen fertilizer is generally applied in jointing stage in rapeseed.