EFFECTS OF DEFICIT IRRIGATION TREATMENTS ON SEED YIELD, OIL RATIO AND WATER USE EFFICIENCY OF SUNFLOWER (Helianthus annuusL.)

The present study was conducted as a field research to investigate the effects of different water deficit levels applied throughout growing season on seed yield, oil ratio and water use efficiency (WUE) of main crop sunflower plants under semi-arid climate conditions of Siirt and Nevsehir provinces in 2015. Irrigation treatments were set as full irrigation (I-100) in which water depletion in 0-90 cm soil profile was fully supplied every week, 25% water deficit (175) in which 75% of full irrigation was supplied and 50% water deficit (I-50) in which 50% of full irrigation was supplied.A total of 6 irrigations were performed in both locations and respectively 400.6 and 373.7 mm irrigation water was applied to I-100 (control) treatment. Plant water consumption of control treatment was measured as 551.0 mm in Siirt and 493.3mm in Nevsehir location.Seed yields in I-100 treatment of relevant locations were respectively observed as 405.7 and 422.2 kgda(-1), oil ratios respectively as 48.2 and 47.8%. The seed yield obtained from 175 treatment was placed in the same group (A) with I-100 treatment in Siirt province and placed in subsequent group (B) in Nevsehir province. In both locations, oil ratio of 175 treatment was placed in the same group (A) with I-100 treatment. Water deficits over 25% resulted in significant decreases in seed yield and oil ratio of sunflower plants. A significant linear relationship (p<0.01) was observed between plant water consumption (ETa) values and seed yields. Average yield response factor (k(y)) was calculated as 0.62, water use efficiency (WUE) as between 0.72-0.96kgda(-1)mm(-1) and irrigation water use efficiency (IWUE) as between 1.01-1.31 kgda(-1)mm(-1).