In order to investigation of rapeseed cultivars reaction to spring and autumn plantings, an experimental was carried out in a split plot design based on RCBD with four replications for two years (2004-2006) in Karaj. Treatments were included planting season in two levels as main plots such as common planting date, autumn planting (27 September) and spring planting (25 March) and spring rapeseed varieties as sub plots in 24 levels. The results indicated that simple effects of planting season and variety and also interaction effect on Pod per plant, 1000 seed weight, seed yield, and harvest index were significant (P<0.01). In autumn planting, Hyola 401 had the highest seed yield (4689 kg.ha-1), whereas RG 405/03 had the maximum seed yield (2066 kg.ha-1) in spring planting.
