Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Agronomy

Two field experiments were conducted at the Agricultural Experiments and Research Station, Faculty of Agriculture, Cairo University, Giza, Egypt during 2014 and 2015 seasons. The objectives of this study were to investigate sunflower development, yield, oil content and its fatty acid profile in relation to variable climate factors. Two open-pollinated sunflower varieties (Giza 102 and Sakha 53) were sown in five sowing dates (May, June, July, August and September) to create variable climate factors (daily, maximum, minimum, average temperature, actual sunshine hours, solar radiation energy) as well as accumulated growing degree days. Results indicated that phenological phases, seed yield and its, components, seed oil contents as well as oleic and linoleic fatty acids were significantly affected by sowing date. Delay sowing date from May to August decreased most of phenological phases which returned to increase for September sowing date. Seed yield and its components gradually decreased by delay sowing date from May to September for both varieties in the two seasons. This was also true for seed oil content. However, oleic acid decreased and linoleic acid increased by delay sowing date from May to September

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