Abstract
The study included two field experiments for sunflower crop conducted during spring growing season of 2008 in two locations. The first was in AL-Rashidia (20 km) west north Mosul city, the second ones was in AL-Hamdanea (30 Km) east of Mosul city. The main objective was to find out the effect of potassium fertilization levels on growth, yield and quality of three sunflower cultivars. Each experiment was conducted according to factorial experiment in a randomized completely block design with three replications. It included three levels of potassium (0, 30 and 60 kg k per hectare-1) were applied to the soil during the sowing period, with three cultivars of sunflower crop (Saturn, Gordis and Majak). The results could be summarized as follows: The cultivar Gordis gave a high level for most growth, yield and quality parameters in both locations. Application of 30 kg K per hectare-1 led to a significant increase in plant height, leaf area, disc diameter, number of seeds per head, weight of thousand seed, seed yield, oil percentage and oil yield, while increasing concentration of potassium up to 60 kg K per hectare-1 caused a significant increase in protein percentage in AL-Rashidia and AL-Hamdanea locations. The interaction between the cultivars and potassium fertilization levels was significant in some growth, yield and quality parameters, the Gordis cultivar with potassium application to the soil with concentration 30 kg k.ha-1 was superior and gave highest values for plant height, stem diameter, leaf area, number of seeds.head-1, weight of thousand seed, oil percentage, oil yield, protein percentage and protein yield in AL-Rashidia location only, while the interaction between cultivars and potassium fertilization levels was significant in number of seeds per head and weight of thousand seed in AL- Hamdanea location only.
