A field trail was conducted at the experimental farm , Field crop station, IPA center for agricultural research , Baghdad , Iraq 2002-2003 season to determine the effects of sowing dates, levels of nitrogen, distance during plants and the interaction between them on seed quality of rapeseed var. Cam-c. Rapeseed was sown in four sowing dates (5 0ct , 25 0ct , 14 Nov, 4 Dec). Every date was sown in a separated experiment. Split- plot design with four replications was used for each date. The main plots included the nitrogen levels (100, 200, 300) Kg N / ha, while the sub-plots included the distance (4, 8, 12)cm between plants.
The results indicated that the first planting date 5 Oct gave the highest percentages of oil, linoleic, linolenic, erucic acids 43.49%, 18.94%, 11.94%, 42.78% and the lowest percentages of protein and oleic acid (27.95%, 9.34%) respectively. Whereas the fourth planting date gave the lowest percentages of oil, linoleic, linolenic, erucic acids 40.64%, 17.09%, 11.29%, 39.85% and the highest percentages of protein and oleic acid 29.81%, 13.4%respectively.The level 300 Kg N. ha-1 gave the highest percentage of protein 29.65% and the lowest percentages of oil, oleic, linoleic, linolenic, erusic acid 41.28%, 16.72%, 17.54%, 11.41%, 39.68% respectively, whereas 100 Kg N.ha-1 gave the lowest percentage of oil, oleic, linoleic, linolenic, erucic acids 42.96%, 11.78%, 18.54%, 11.70%,42.69%respectively.The intra-spacing 4cm gave the highest percentages of oil, oleic, linolenic, erucic 42.38%, 11.46%, 11.9%. 41.80%,and the lowest percentage of protein 28.73% whereas the intra- spacing 12cm gave the lowest percentages of oil, oleic, linolenic, erucic 41.84%, 11.08%, 11.47%, 40.70% and the highest percentage of protein 28.90% respectively.
The interaction between the fourth planting date 4 Dec with 300 Kg N.ha-1 gave the highest protein percentage 30.02% and the lowest erucic acid percentage 38.14% while the first planting date 5 Oct with 100 Kg N.ha-1 gave the lowest protein percentage 27.54 and the highest percentage of erucic and linolinc acids44.12%,9.18respectively.It was concluded that early planting date gave the highest percentages of oil and erucic acid which is suitable for industrial purposeswhereas the oleic percentage increased in late planting .