Evaluation of phytochemical profiles and relationships of compounds in Lippia citriodora during multiple growth-exploitation phases

Abstract

In the present study the variations of biomass, essential oil content and composition of lemon verbena (Lippia citriodora) during different growth-exploitation phases from 27th May 2020 to 8th June 2021 were investigated. The uniform rooted cuttings were planted in the greenhouse under natural light. The aerial parts of lemon verbena at flowering stage were harvested at six times included 27th May (H1), 29th August (H2), 4th November (H3), 17th January (H4), 27th March (H5), and 8th June (H6). Hydro distillated essential oils were analyzed by using GC-FID and GC/MS techniques to determine the essential oil profile. Results showed a considerable variation in plant biomass, essential oil quantity and quality at different harvesting times. Plant biomass increased by 66.83% up to fourth harvesting time (H4) then decreased. During the studied harvesting frequencies the essential oil content of L. citriodora showed a sinusoidal trend. The highest essential oil content (0.858% v/w) and yield (17.95 L ha−1) were obtained at third harvesting time (H3) and in the followed harvesting times their contents were decreased. The observed changes in the essential oil composition of L. citriodora during different harvesting times were due to the relative proportions of constituents and the presence of new constituents. In the all essential oil samples, oxygenated monoterpenes represented by geranial (25.42–30.11%) and neral (19.81–24.19%) were the predominant compounds. The highest ratio of monoterpenes to sesquiterpenes compounds (≈5:1) was recorded in collected plants at third harvesting time.