The effect of different irrigation water levels on yield and quality characteristics of purple basil (Ocimum basilicum L.)

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. (C) 2012 Elsevier B.V. All rights reserved.