GC-MS and GC-FID analyses of the essential oil of Eucalyptus camaldulensis grown under greenhouses differentiated by the LDPE cover-films

Abstract

The chemical composition of essential oils (EOs) can vary from one plant to another of the same species and can be affected by several factors including the environment of growth. The research was carried out on the EOs of Eucalyptus camaldulensis leaves grown in three separate greenhouses differentiated by their low-density polyethylene (LDPE) covering material. This study aimed to compare the impact of the type of the greenhouse cover film on the internal microclimate, light intensity, and chemical composition of E. camaldulensis EOs. Eucalyptus species was initially cultivated from the seeds and the EOs were extracted from the leaves of 14 weeks aged trees. The extraction was performed by hydrodistillation using a Clevenger-type apparatus. Qualitative and quantitative analyses of the extracted EOs were performed using gas chromatography coupled with mass spectrometry (GC-MS) and gas chromatography coupled with a flame ionization detector (GC-FID). The analyzed samples were rich in terpenes with a total of 66 identified compounds. The oxygenated monoterpenes pinocarvone and D-carvone were only identified in the essential oils from multilayered greenhouses. cis-1-Methyl-4-(1-methylethyl-)-2-cyclohexen-1-ol was absent in eucalyptus EOs from the three-layer greenhouse, unlike the others that had it. Different compound contents were detected in the extracted essential oils, according to their greenhouse cover conditions. 1,8-Cineol was the compound present in a higher amount as expected, with the highest value of c.a 164.78 mg/gdw from the leaves of E. camaldulensis cultivated in the ordinary greenhouse. Contents of 51.55 mg/gdw and 42.11 mg/gdw were obtained from E. camaldulensis cultivated in the three-layers and monolayer greenhouses, respectively. In contrast, the EOs of E. camaldulensis grown under the monolayer greenhouse presented the highest content of some aromadendranes family compounds. This study shows that the greenhouse cover-film should be chosen thoughtfully because it plays a major function regarding its effect on the chemical composition of the EOs of E. camaldulensis cultivated in greenhouse environments.