Comparision of the yield and quality parameters of certain ‘kekik’ species grown in central turkey

A collection of oregano, thyme and summer savory plants were seeded and grown in an experimental field at the Central Research Institute for Field Crops in Ankara, Turkey, to investigate the biomass and foliage production, essential oil, and carvacrol and thymol during the years of 2009 and 2010. The following yield parameters were observed and measured with two cuttings from each growing season. The total green herb yield of the two harvests ranged from 17.12 t/ha to 52.74 kg/ha in 2009 and 15.46 t/ha to 69.55 t/ha in 2010. The total dry herb and dry leaf yields were; 4.82–15.37 t/ha and 4.54–21.1 t/ha; and 2.23–511 t/da and 3.10–10.8 t/ha in two successive years, respectively. The average essential oil ratio of the kekik species changed from 1.42% to 6.08% and 1.30–5.43%. Despite most previous studies emphasizing carvacrol as the major constituent of O. onites and O. vulgare var. hirtum species in the natural flora of Turkey, the current study detected thymol (a high of 67.45%) as major a constituent in these plants. CV Carva had the highest content of carvacrol with 58.76% and 74.71%. Among the studied kekik species only Thymus citriodorus was found to contain geraniol with 49.13% and 36.36% contents.