Industrial Crops and Products 41 (2013) 1–9 Contents lists available at SciVerse ScienceDirect Industrial Crops and Products journa l h o me page: www.elsevier.com/locate/indcrop Selection of A clones from Thymbra spicata var. spicata by clonal selection method Süleyman Kızıl ∗ Department of Field Crops, Agriculture Faculty, Dicle University, 21280 Diyarbakir, Turkey a r t i c l e i n f o Article history: Received 23 January 2012 Received in revised form 4 April 2012 Accepted 5 April 2012 Keywords: Thymbra spicata var. spicata Southeastern Anatolia & Mediterranean Regions Clone selection A-Clones Fresh & dry herbage yield Carvacrol a b s t r a c t The main objectives of our research were: (1) to evaluate clones among 28 locations of Thymbra spicata populations from the South-eastern Anatolia and Mediterranean region of Turkey, (2) comparing phyto- chemical content between populations under cultivated conditions, (3) to determine possible correlations between phytochemical content and morphological traits, along with (4) identifying yield-related traits for use in clonal selection programs. The investigated characters were plant height, plant canopy diame- ter, spike length, fresh herbage weight per plant, dry herbage weight per plant, dry leaf weight per plant, stem weight per plant, leaf/stem ratio and essential oil content per plant. Statistical analysis showed that populations had significant effect on most morphological parameters except stem weight per plant. Sim- ple correlation analysis showed that dry leaf weight had significant and positive correlation with plant height, canopy diameter, fresh herbage and dry herbage (r = 0.623, 0.784, 0.954 and 0.983, respectively). Major compounds of essential oil of T. spicata are carvacrol, alpha-terpinene, 4-terpineole, 4-carene and alpha phellandrene. Carvacrol content of different populations ranged 62.2–78.8%. Due to high variabil- ity among wild populations these were considered important sources for breeding. The results further emphasize the possibility of selecting high yielding clones with high agronomic traits for development of a new variety or varieties, which will definitely reduce pressure on the nature for obtaining these plants. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Thyme volatile oil has been reported among the top 15 essen- tial oils (Letchamo et al., 1995) and is used widely in food and cosmetic industry (Baser, 2001). Previous studies indicate the anti- septic, carminative, antimicrobial and antioxidant properties of thyme species (Markovic et al., 2011; Svoboda et al., 1993). The thyme species including Thymbra spicata is largely har- vested from the wild populations in the world. There is no chemically homogeneous and standardized raw material in respect to essential oil components, such as thymol, carvacrol and limonene type. Carvacrol is the predominant monoterpenic phenol in many essential oils of the family Lamiaceae including Origanum, Sat- ureja, Thymbra, Thymus and Corydothymus species (Loziene, 2009). Among oil compounds, carvacrol,  terpinene, p-cymene com- ponents account for 70% of essential oils of T. spicata. Carvacrol predominates (>80%) among all essential oils (Kizil, 2010; Markovic et al., 2011). Moreover, -pinene, myrcene, -terpinene, - terpinene, -terpinene, 1,8 cineol, p-cymene, -caryophyllene, -terpineol and thymol are also found in essential oils of T. spicata ∗ Tel.: +90 412 2488509; fax: +90 412 2488153. E-mail addresses: kizils@dicle.edu.tr, suleymankizil@gmail.com (Hanci et al., 2003; Baydar et al., 2004). Besides this, other com- ponents are also found in trace amounts among essential oils of T. spicata. In evaluating the essential oil composition one has to keep in mind that oil production is governed by numerous factors. They include genetic variability, physiological variation, such as organ development, pollinator activity, seasonal variation, mechanical or chemical injuries, and also other environmental conditions, such as edaphic factors like climate, pollution, diseases and pests (Akgul, 1993; Figueiredo et al., 2008; Chizzola, 2010). Among commercially important crops, there are many species belonging to temperate and subtropical origin, from Lamiaceae that can be successfully grown in the tropics whereas most of the crops from tropical origin cannot easily be grown in other geoclimatic regions. Plant improvement in tropical and semi-arid crop plants is traditionally done by cloning of selections. Many among them are vegetatively propagated self-incompatible crops and can breed difficultly (Bhat, 1995). Based on some desired phenotypic charac- ters, planting material can be selected from a healthy and better yielding mother plant for vegetative propagation. Both the raw material of medicinal and aromatic plants and their products must meet the maintenance of high standards required on quality, safety and efficiency. This can only be fulfilled by cultiva- tion of plants which are selected according to particular biological and chemical characteristics. The natural habitats of plants are big reserve for the selection of the new cultivars. 0926-6690/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2012.04.013