title: Seasonal variations in the composition of the essential oils of rosemary (Rosmarinus officinalis, Lamiaceae).
abstract: Seasonal variations in the composition of the essential oils obtained from rosemary plants of the same genotype cultivated in Belgrade were determined by GC and GC/MS. The main constituents were camphor (18.2 - 28.1%), 1,8-cineole (6.4-18.0%), alpha-pinene (9.7-13.5%), borneol (4.4-9.5%), camphene (5.1-8.7%), beta-pinene (2.1-8.1%), beta-phellandrene (4.6-6.5%), myrcene (3.4-5.9%) and bornyl acetate (0.2-7.9%). Cluster analysis showed that 16 samples that had been collected each month during the vegetative cycle can be separated into three main clades with different compositions of essential oils. In the shoots with fruits ('fruits' - Clade I) and shoots with developed leaves ('old shoots' - Clade III) camphor is dominant. In shoots with young and incompletely developed leaves ('young shoot' - Clade II) camphor and 1,8-cineole had almost the same concentration. The fact that the same genotype during the growing seasons can synthesize oils that are so different that they can be classified as different chemotypes confirms the opinion that the chemical composition of essential oils sometimes critically depends on the time of collection. Also, for the definition of chemotypes it is not enough to base this on a chemical analysis of an oil from one phenophase only.
authors.affiliation: Institute of Botany and Botanical Garden "Jevremovac", Faculty of Biology, University of Belgrade, Takovska 43, 11000 Belgrade, Serbia.
authors.forename: Dmitar
authors.initials: D
authors.lastname: Lakusić
authors.forename: Mihailo
authors.initials: M
authors.lastname: Ristić
authors.forename: Violeta
authors.initials: V
authors.lastname: Slavkovska
authors.forename: Branislava
authors.initials: B
authors.lastname: Lakusić
mesh_terms: D016000:Cluster Analysis; D009822:Oils, Volatile / Q000737:chemistry*; D027542:Rosmarinus / Q000737:chemistry*; D012621:Seasons
chemical_list: D009822:Oils, Volatile