Effects of Winter Cultivation on Sunflower Cultivars Seed Yield in the North of Khuzestan ‎Province

In order to develop winter cultivation and improve crop rotation in the region, an experiment has been conducted to evaluate the effects of sowing date on sunflower cultivars seed yield. It is a split-plot based on completed randomized blocks design with four replications in Safiabad Agricultural and Natural Resources Research and Education Center of Dezful and has taken place during two years (2015-2016). The main plots are consisted of four sowing date levels (23rd Jan, 6th Feb, 20th Feb, and 6th Mar), while the sub plots include nine levels of cultivars (Azargol, Armavirski, Barzegar, Progress, Record, Shams, Farokh, Ghasem, and Gabor). Delay in the sowing date has decreased growth period length and plant height, with the greatest number of seeds per capitulum (684.17) belonging to record cultivar on the first sowing date in the first year and the maximum one (767.47) occurring again to this cultivar on the third sowing date in the second year. The maximum seed yield in the first (3850 kg.ha-1) and second (4088 kg.ha-1) year belong to the first sowing date (23rd Jan) and Azargol cultivar. Based on the results, Azargol cultivar have had the lowest rank, being considered as the cultivar with the highest seed yield on all sowing dates, followed by Record and Armavirski, in the second and third placed, respectively. In terms of stability, considering that Farrokh cultivar also has had the lowest standard deviation, it has been selected as the most stable cultivar.