Evaluation of Seed Yield and Related Components of Rapeseed Winter Cultivars Under Different Sowing Dates in Karaj Area-Iran

Sowing date is the most important factor affecting yield and it''s components of rapeseed. Suitable sowing dates make the environmental conditions favorable for plant during the days of seedling emergence and its establishment. This experiment was conducted in split plot layout with randomized complete block design with four replications at Seed and Plant Improvement Institute (SPII) during 2000–2002 years. Main plots were sowing date with four levels of: Sept. 11، Sept. 21، Oct. first and Oct. 11. Sub-plots were rapeseed varieties including SLM046، Zarfam، Colvert and Orient. The traits evaluated were: Plant height، number of branches، number of pods per plant، number of seeds per pod، 1000 seeds weight، seed yield، oil contain and oil yield. Combined analysis of variance showed that sowing date had significant effect on seed yield، oil yield، number of pods per plant، number of branches and 1000 seeds weight (p<0. 01). The highest yield (3295 and 2877 kg/ha) was in the first planting time (Sept. 11) and the second planting time (Sept. 21)، respectively. Variety effect was highly significant only for number of seeds per pod and 1000 seed weight. The highest number of seeds per pod was related to SLM046 and Orient varieties (24. 3 and 24. 2، respectively). Interaction between sowing date and variety was significant only for number of branches and number of seeds per pod (p<0. 05). The results of this experiment show that the most suitable sowing date at Karaj is from 11th to twenty-one of September and decrease in seed yield occurs due to significant decrease in yield components، when planting time is delayed.