In order to study the effect of planting date and different levels of nitrogen on yield and growths of nuts sunflower (var. Doursephid), an experiment was conducted at Mahoodabad Experimental Field in Isfahan, in 2009. A split plot layout within a randomized complete block design with 3 replicates was used. The treatments in the main plots were sowing dates (May 5th and 20th and June 5th) and in the subplots treatments were nitrogen levels (0, 150, 200 and 250 kg N/ha). Results showed that the effect of planting date was significant on stem diameter, head diameter, number of grain per head, grain yield and biological yield. The effect of different levels of nitrogen was significant on plant height, stem diameter, biological yield and harvesting index. Interaction between planting date and nitrogen had significant influence on plant height, stem diameter, biological yield and harvesting index. The highest stem diameter, head diameter, grain yield and total yield was obtained in May 5th, and the highest plant height, stem diameter, head diameter, number of grain per head, 1000 grain weight and grain yield was obtained from usage of 200 kg N/ha. Results showed that 200 kg N/ha and May 5th is suitable for this variety in this region.
Key words: Planting date, nitrogen, nut sunflower, yield and yield components.
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