الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Three field experiments in each planting date for each winter season of 1997/98 and 1998/99 were carried out at an extension field at Kafr Yusuf Village, Sherbien District, Dakahlia Governorate, Egypt. This investigation was aimed to study three cultivars performance under three sowing dates, three nitrogen fertilizer levels and their interactions for growth, yield and yield components traits as well as seed oil percentage and oil yield of oilseed rape (Brassica napus, var. oleifera, L.). A split plot design with three replicates was used in each experiment, which included three cultivars and three nitrogen fertilizer levels. The main plots were allocated with the three oilseed rape cultivars i.e. Serw 4, Jencea 10/2 and Pactol and the three nitrogen fertilizer levels i.e. 35, 50 and 65 kg N/fad were assigned in the sub plots. Combined analysis over the three planting dates was done in each season. Planting Jencea 10/2 and/or Pactol cultivars on the first of November and adding the highest nitrogen fertilizer dose of 65 kg N/fed produced the highest number of siliqua per plant, 1000seed weight, seed yield per plant as well as seed, straw and oil yields per feddan in both seasons. 1.?In both seasons, all the interactions between sowing dates, oilseed rape cultivars and nitrogen fertilizer levels had insignificant effect on oil percentage except for the interaction between planting dates and oilseed rape cultivars. The results indicated that, planting Jencea 10/2 cultivar on midOctober or on the first of November produced the highest oil percentage in both seasons. Conclusions It could be concluded that maximizing seed yield of oilseed rape per unit area could be achieved by planting Pactol cultivar on the first of November with adding nitrogen fertilizer dose of 65 kg N/fed under the environmental conditions of North of Dakahlia Governorate.