Study of rapeseed cultivars reaction to different sowing date in Karaj region

This experiment was done to study the effect of sowing date on grain and oil yield، yield components and some characteristics of 6 rapeseed genotypes. It conducted as a factorial on the basis of RCBD with three replications in research field of seed and plant improvement institute during 2005-2007. Sowing dates factor were selected in 3 levels include of 6th September، 16th September and 6th October and cultivars factor were Talaye، SLM046، Okapi، Orient، Licord and Zarfam. The result showed that the sowing date and cultivar effects were significant on all criteria exception the seed numbers in silique and، plant height and biological yield، respectively. Two sowing dates were superior to third sowing date in the point of grain and oil seed yield، harvest index and biological yield. Among yield components، seed numbers in silique and silique numbers in plant were higher in the second sowing date and 1000 seed weight was greater in the first sowing date. Cultivars yield didn’t have significant differences because every one of them was superior to other in the point of one of the yield component. But the oil percentage difference among cultivars caused to create significant differences in the point of oil seed yield among them.