Effect of different sowing date on yield and yield components seed of spring rapeseed cultivars

In order to determine the grain yield and other characters of spring rapeseed cultivars under varying sowing dates, an experiment was conducted at cultural experiment and research center, faculty of agriculture, Islamic Azad University, Khorasghan Branch, Isfahan. (latitude 32o 40/ N, longitude 51o 58/ E, and 1570 m elevation). The experimental design was a split plot in completely randomized block lay out with three replications. Four sowing dates (27 Feb, 9 Mar, 19 Mar and 28 mar) and four rapeseed cultivars (RGS003, PF7045-91, Option 500 and Hyola 401) as subplots. Results showed that the effect of sowing date on all experimental factors, was significant. Also, effect of cultivars number of grain per main silieques and oil seed rate, was significant. The interaction between sowing date and cultivar has significant effects on the number of grain per main silique, a thousand grain weight and oil percentage. In the view of the sensitivity of rapeseed to climatic factors especially to photoperiod and temperature, it is essential that sowing should be done on time, so that there have enough time for vegetative growth. According to the results obtained during two years, RGS003 cultivar at the first planting date recommended for sowing in Isfahan province.