Agricultural Water Management 109 (2012) 155–161 Contents lists available at SciVerse ScienceDirect Agricultural Water Management j ourna l ho me page: www.elsevier.com/locate/agwat The effect of different irrigation water levels on yield and quality characteristics of purple basil (Ocimum basilicum L.) Sıdıka Ekren a,∗ , C ¸ i˘ gdem Sönmez a , Emrah Özc ¸ akal b , Yasemin S. Kukul Kurttas ¸ b , Emine Bayram a , Hatice Gürgülü b a Field Crops Department, Faculty of Agriculture, Ege University, 35100 Bornova, Izmir, Turkey b Irrigation and Agricultural Structures Department, Faculty of Agriculture, Ege University, 35100 Bornova, Izmir, Turkey a r t i c l e i n f o Article history: Received 27 June 2011 Accepted 13 March 2012 Available online 10 April 2012 Keywords: Ocimum basilicum Essential oil Water stress Water use efficiency a b s t r a c t A field study on purple basil (Ocimum basilicum L.) was carried out to determine the effect of different irrigation water levels in 2007 and 2008 in the research field of Ege University, Faculty of Agriculture, in Turkey. Four irrigation treatments were determined as the irrigation water being needed to raise root zone soil water to field capacity (I 100 : 100%, at field capacity) and a percentage of water applied to I 100 treatment (I 50 : 50%, I 75 : 75% and I 125 : 125% of field capacity). The effect of different irrigation water levels on purple basil’s plant height, green herb yield, drug herb yield, and drug leaf yield, the irrigation water use efficiency, essential oil ratio, and composition of essential oil were evaluated. According to the results, the highest plant height (38.6 cm), green herb yield (2269.4 kg da -1 ), drug herb yield (417.2 kg da -1 ), drug leaves yield (300.6 kg da -1 ) were determined in the I 125 treatment for both years. However, the highest essential oil ratio (1.10%) was found in the I 50 treatment. The results revealed that purple basil plant is sensitive to water stress or the amount of irrigation water applied. Water stress negatively affected the plant height and the yields of purple basil plant. On the contrary, the essential oil ratio of the plant increased as the applied amount of irrigation water decreased. Water stress has a positive effect on essential oil composition of the plant. The main components of the essential oil were linalool, eugenol and methyl chavicol. Since the yields changed in parallel with the amount of irrigation water applied, the irrigation water use efficiencies were not significantly different according to the irrigation water levels. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Basil (Ocimum basilicum L.) is a member of the Lamiaceae fam- ily, which is a widely grown aromatic crop cultivated either for the production of essential oil, dry leaves for the market, or as an orna- mental (Topalov, 1962; Simon et al., 1990). Basil comprises annual and perennial herbs, and shrubs native to the tropical and sub- tropical regions of Asia, Africa and South America (Darrah, 1988). Approximately, 60 species of basil are known throughout the world and cultivated in France, Egypt, Hungary, Indonesia, Morocco, The United States, Greece and Israel (Srivasta, 1980). The useful parts of the basil plant are its leaves and seeds. Basil has been utilized for headaches, coughs, worms, stomach-ache and kidney malfunctions in medical treatments (Simon et al., 1990). In addition, both the fresh and dry leaves of the plant are very com- monly used in food and spice industries. Furthermore, it is also ∗ Corresponding author. Tel.: +90 232 3112299; fax: +90 232 3432474. E-mail address: sidika.ekren@ege.edu.tr (S. Ekren). considered as a source of aroma compounds and thus, possesses a range of biological properties such as insect repellent, nemato- cidal, antibacterial, antifungal agents and antioxidant properties (Deshpande and Tipnis, 1977; Simon et al., 1990; Juliani and Simon, 2002; Lee et al., 2005). The essential oil ratio varies between 0.1 and 0.45% based on differing climate and soil conditions (Ceylan, 1997). The essential oil of the basil plant is used in the food industry as a flowering agent and also in perfumery and medical industries (Simon et al., 1990). The major components of the oil are linalool, estragole, methyl cin- namate, eugenol, 1,8-cineole (Juliani and Simon, 2002; Lee et al., 2005), methyl chavicol, geranial, neral and caryophyllene oxide (Sajjadi, 2006). The plant of basil (O. basilicum L.) has been studied extensively in various research works to determine yield, yield components, the essential oil ratio and the composition of the essential oil, fer- tilization and plant densities under different ecological conditions, but only a limited amount of research has focused on the effects of the amount of irrigation water applied. Khalid (2006) reported that O. basilicum L. and Ocimum amer- icanum L. potted seedlings were treated with different levels of 0378-3774/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2012.03.004