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Effect of sowing date and plant density on rapeseed varieties

In order to study the effects of sowing date and plant density on vegetative characters, yield and yield components of rapeseed varieties, an experiment was conducted at Agricultural Research Station of Gonbad during 2000 - 2002. The experiment was a split factorial arranged in a RCBD with 4 replications. Four sowing dates (Oct. 22nd, Nov. 6th. Nov. 21st and Dec. 6th) were as main plots and two varieties (Sarigol and Hyola 441) and two row spacing (24 and 36 cm) were subplots in a factorial arrangement.The results of combined analysis for two year showed that plant height, the number of days from emergence to flowering and physiological maturtte duration of flowering and number of pod per plant decreased significantly with delay in sowing date. The number of grams per pod and 1000 gram weight of Hyola 401 hybrid were more than those ofSangol variety. The number of pod per plant and the number of grains per pod in 36 cm row spacing were more than those of 24 cm row spacing, however 1(0)0 grain weight of 24 cm row spacing was greater than that of 36 cm. Generally grain yield of rapeseed decreased with delay in sowing date. The first sowing date had the highest grain yield (4513 kg/ha), whereas the fourth sowing date produced the lowest grain yield (3228 kg/ha). The grain yield of Hyola 401 hybrid (4139 kg/ha) was more than Sarigol variety (3550 kg/ha). The grain yield of 24 cm row spacing was more than that of 36 cm row spacing .The grain yield of row spacing 24 and 36 cm were 4238 and 3451 kg/ha ,respectively. The combination of first sowing date, Hyola 401 hybrid, and 24 cm row spacing treatment produced the highest grain yield (5169 kg/ha).