Determination of the best sowing date of new varieties of canola in Golestan province

In order to study the effects of sowing date on vegetative characters, yield and yield components of Four varieties of canola, an experiment was conducted at agricultural research station of Gonbad and Gorgan during 2002–2004. The experiment was a split plot arranged in a RCBD with 4 replications. Four sowing dates (Nov. 6th, Nov. 21st, Dec. 6th and Dec. 21st) were as main plots and four varieties (Hyola 401, Syn-3, Quantum and Option 500) were subplots. Gonbad The results of two combined analyses showed that the number of days from emergence to flowering and physiological maturity and prewinter growth decreased significantly with a delay in sowing date. The grain yield of first and second sowing date was significantly more than that of third and forth sowing date. The grain yield of first, second, third and fourth sowing date was 3417, 3431, 2945 and 2358 kg/ha, respectively. The number of days from emergence to physiological maturity in first year of experiment (166 days) was more than that of second year of experiment (151 days), because of the higher temperature in duration of growth in second year. The lodging happened just in first sowing date of first year of experiment. Hyola 401 Hybrid had the highest grain yield, because of the highest prewinter growth, the number of pod per plant and 1000-grain weight.. The mean grain yield of Hyola 401, Syn-3, Quantum and Option 500 varieties was 3457, 2863, 2763 and 3068 kg/ha, respectively. Hyola 401 hybrid and sowing date of Nov. 6th to Nov. 21st recommends for Gonbad and Kalaleh area with regard to results of two years of experiments. Gorgan The results of two combined analyses showed that the number of days from emergence to flowering and physiological maturity, the number of pod per main stem and grain yield decreased significantly with a delay in sowing date. The grain yield of first, second, third and fourth sowing date was 3034, 2689, 2325 and 1024 kg/ha respectively. The number of days from emergence to physiological maturity in first year of experiment (166 days) was more than that of second year of experiment (159 days), because of the higher temperature in duration of growth in second year. Hyola 401 Hybrid had the highest grain yield, because of the highest the number of pod per main stem and 1000-grain weight. The mean grain yield of Hyola 401, Syn-3, Quantum and Option 500 varieties was 3284, 2160, 2737 and 1791 kg/ha, respectively.