Agricultural Water Management 98 (2011) 1153–1161 Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat Comparison of drip and sprinkler irrigation strategies on sunflower seed and oil yield and quality under Mediterranean climatic conditions S.M. Sezen a,∗ , A. Yazar b , B. Kapur b , S. Tekin b a Department of Water Management, Soil and Water Resources, Tarsus Research Institute, PO Box 23, 33400, Tarsus, Mersin, Turkey b Department of Irrigation and Agricultural Structures, Faculty of Agriculture, Cukurova University, 01330, Adana, Turkey article info Article history: Received 25 June 2010 Accepted 10 February 2011 Available online 11 March 2011 Keywords: Deficit irrigation Water productivity Partial root-zone drying Oil content Oil yield response factor abstract This study compares the effects of different irrigation regimes on seed yield and oil yield quality and water productivity of sprinkler and drip irrigated sunflower (Helianthus annus L.) on silty-clay-loam soils in 2006 and 2007 in the Mediterranean region of Turkey. In sprinkler irrigation a line-source system was used in order to create gradually varying irrigation levels. Irrigation regimes consisted of full irrigation (I 1 ) and three deficit irrigation treatments (I 2 ,I 3 and I 4 ), and rain-fed treatment (I 5 ). In the drip system, irrigation regimes included full irrigation (FI-100), three deficit irrigation treatments (DI-25, DI-50, DI-75), partial root zone drying (PRD-50) and rain-fed treatment (RF). Irrigations were scheduled at weekly intervals both in sprinkler and drip irrigation, based on soil water depletion within a 0.90 m root zone in FI-100 and I 1 plots. Irrigation treatments influenced significantly (P < 0.01) sunflower seed and oil yields, and oil quality both with sprinkler and drip systems. Seed yields decreased with increasing water stress levels under drip and sprinkler irrigation in both experimental years. Seed yield response to irrigation varied considerably due to differences in soil water contents and spring rainfall distribution in the experimental years. Although PRD-50 received about 36% less irrigation water as compared to FI-100, sunflower yield was reduced by an average of 15%. PRD-50 produced greater seed and oil yields than DI-50 in the drip irrigation system. Yield reduction was mainly due to less number of seeds per head and lower seed mass. Soil water deficits significantly reduced crop evapotranspiration (ET), which mainly depends on irrigation amounts. Significant linear relationships (R 2 = 0.96) between ET and oil yield (Y) were obtained in each season. The seed yield response factors (ky seed ) were 1.24 and 0.86 for the sprinkler and 1.19 and 1.06 for the drip system in 2006 and 2007, respectively. The oil yield response factor (ky oil ) for sunflower was found to be 1.08 and 1.49 for both growing seasons for the sprinkler and 1.36 and 1.25 for the drip systems, respectively. Oil content decreased with decreasing irrigation amount. Consistently greater values of oil content were obtained from the full irrigation treatment plots. The saturated (palmitic and stearic acid) and unsaturated (oleic and linoleic acid) fatty acid contents were significantly affected by water stress. Water stress caused an increase in oleic acid with a decrease in linoleic acid contents. The palmitic and stearic acid concentrations decreased under drought conditions. Water productivity (WP) values were significantly affected by irrigation amounts and ranged from 0.40 to 0.71 kg m -3 in 2006, and from 0.69 to 0.91 kg m -3 in 2007. The PRD-50 treatment resulted in the greatest WP (1.0 kg m -3 ) and irrigation water productivity (IWP) (1.4 kg m -3 ) in both growing seasons. The results revealed that under water scarcity situation, PRD-50 in drip and I 2 in sprinkler system provide acceptable irrigation strategies to increase sunflower yield and quality. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Availability of water rather than land is the main constraint on agricultural production in arid and semi-arid environments and the most important factor limiting plant performance and yield world wide. Review of current trends of water availability ∗ Corresponding author. Tel.: +90 324 644 64 78x116; fax: +90 324 644 60 90. E-mail address: smsezen@hotmail.com (S.M. Sezen). (FAO, 2002) indicated that agricultural activities are approaching a “water crisis” in several regions, most notably in the Mediterranean region. The major agricultural use of water is for irrigation, which is affected by decreased supply. Therefore, improvement in crop water productivity (WP) in agricultural is of strategic importance. Both deficit irrigation (DI) and partial root-zone drying (PRD) are water-saving irrigation strategies (English and Raja, 1996; Kirda et al., 2005). PRD technique has been reported by Kang and Zhang (2004) and Davies and Hartung (2004) to have the potential to reduce field-crop water use significantly, increase canopy vigour, 0378-3774/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2011.02.005