عنوان مقاله [English]
In order to evaluate the possibility of autumn/winter planting of new oilseed sunflower genotypes under rainfed conditions of Gonbad, an experiment was conducted at the agricultural research station of Gonbad over 2 years (2008-2010). A split-plot design arranged in RCBD with four replications was used. Four planting dates (starting from 1st December with 15 day intervals) and 6 sunflower genotypes (SHF81-90, Farrokh, Favorit, Azargol, CMSG5*R-43, CMSG6*R-43) were the levels of main and sub-plots, respectively. The studied traits were stem and head diameter, plant height, growth period, 1000-seed weight, grain yield, oil content and oil yield. The effect of genotype was significant on all traits studied except oil content. Hybrids CMSG6*R-43 and SHF81-90 had the highest (1.889 t/ha) and lowest (1.385 t/ha) seed yields, respectively. Thousand-seed weight and growth period decreased while plant height increased with a delay in planting. The studied traits responded differently to planting dates in two years. Although seed yield was significantly affected by planting dates, only in the second year, two-year mean of the seed yield indicated the superiority of the second planting date. To obtain higher seed and oil yield under rainfed conditions of Golestan province in years with lower rainfall, we recommend sowing of late maturing hybrids i.e CMSG5*R-43 and Azargol in autumn. In years with suitable rainfall, we might suggest sowing of OP cultivar Favorit because of its lower production cost and higher net income.