Effect of Transplanting Date on Seed Yield and Its Components of Four Rapeseed (Brassica napus L.) Cultivars as Second Crop in Rasht in Iran

To study of the effect of transplanting date on seed yield and its components in four rapeseed cultivars this research was carried out in paddy fields of Rice Research Institute of Iran, Rasht, Iran, in three successive cropping seasons (2004-2007)- Using split plot arranagements in randomized complete block design with three replications. Five transplanting dates; October 23 (Mean air temp. 17.3ºC), November 06 (Mean air temp. 16.8 ºC) and 22 (Mean air temp. 15 ºC), December 06 (Mean air temp. 10.1 ºC) and 21 (Mean air temp. 8.3 ºC) were assigned to main plots, and four rapeseed cultivars; Hayola 401, Hayda 308, RG 003 and Sarigol were randomized in sub-plots. Transplanting was done by hand at 5-6 leaf stage with row spacing of 25 cm and between plant distance 8 cm. Combined analysis of variance showed that the effect of year, transplanting date and cultivar was significant on the majority of traits. Second transplanting date with 2740 kgha-1 and Hayola 401 with 2851 kgha-1 produced the highest average seed yield. Hayola 401 in the second transplanting date had the highest average seed yield (3247 kgha-1). Hayola 308 in fifth transplanting date completed its life cycle (151 days) earlier than the other cultivars. The highest oil harvest index (15.25%) also belonged to Hayola 401. In conclusion, transplanting can be successfully practiced for these four rapeseed cultivars from 23 October (Mean air temp. 17.3ºC) to 22 November (Mean air temp. 15 ºC) with the highest seed yield in the early November in Rasht region.