Herb yield and chemical composition of basil (<i>Ocimum basilicum</i> L) essential oil in relation to the different harvest period and cultivation conditions

Abstract

Background: Ocimum basilicum L., commonly known as sweet basil, is an important aromatic plant cultivated in many parts of the world for its essential oil. Basil does not show natural distribution in Turkey but they are cultivated as medicinal, seasoning or oil plants especially in the western and southern Anatolia. In this study, introduction of new production patterns of green and purple basil into Rize province in the northern parts of Turkey is the main objective of the present study. In this context, herb yield and chemical composition (essential oil and its components) of green and purple basil plants grown under open field and underneath or between kiwi plantations were determined and compared. Materials and Methods: The experiments were arranged as a split plot design with three replications in May in 2010 and 2011 in open-field conditions and between kiwi plantations. Three harvests were done for each year. After each harvest, above ground parts were dried at 35 oC and essential oils from aerial parts after each harvest were extracted using 30 g of dried material by hydro distillation (4 h) with Neo-Clevenger apparatus. The essential oil compositions were identified by GC-MS. Results: There were decline trends with respect to the plant height, fresh and dry herb yield in the second year. For both experimental years, the highest fresh and dry herb-yields were obtained in open-field conditions in green basil. There were no statistically significant differences in relation to essential oil yield in open-field conditions and kiwi plantations but the highest essential content was ascertained in open-field conditions for green basil. The major aroma constituents of basil were methyl cinnamate and linalool and the highest percentage was determined in open-field conditions for green basil. Conclusion: The lowest essential content obtained in open-field and between kiwi plantations for green and purple basil plants was even higher than the limit (%0.3) established by Turkish Standards Institution and total yield concerned with fresh and dry herb yield complied with the previously proposed literatures. Hence, basil cultivation underneath kiwi plantations may be implemented.