Effect of different nitrogen levels on yield components and seed yield of three sunflower (Helianthus annuus L.) cultivars

In order to study the effect of different nitrogen levels on yield components and seed yield of three sunflower cultivars, an experiment was conducted during 2010-11 at a research farm of farming building of Islamic Azad University, Khorasgan (Esfahan) Branch located in Khatun abad village (latitude 32 degrees 40 ' N and longitude 51 degrees 48 ' E). A split plot layout within randomized complete block design with three replications was used. Main plots were different levels of nitrogen fertilizer (0, 100, 150 and 200 kg/ha) from urea source, and sub-plots were different cultivars (Sanbro, Sirna and Hai.sun33). Condition represented that the effect of N fertilizer was significant on head diameter, 100-seed weight, seed yield, biological yield, oil percentage and oil yield.150 kg N/ha fertilizer treatment resulted in the maximum of all mentioned factors. Effect of cultivar was significant on head deep, seed number of head, 100-seed weight, seed yield, biological yield, oil percentage and oil yield. The maximum of all mentioned factors except oil percentage were related to Hai.sun33. Interaction of nitrogen and cultivar was significant on 100-seed weight, seed yield, oil percentage and oil yield. On the basis of the results obtained, the fertilizer treatment 150 kg N/ha and Hai.sun33 might be suitable for sunflower production under the condition similar to the present study.