The Effects of Carbon Dioxide and Temperature on Essential Oil Composition of Purple Basil (Ocimum basilicum L.)

Abstract

Purple basil is one of the most important morphological varieties of basil. The present study aims to determine the changes in the essential oil composition and specific phenolic acid contents of purple basil in response to the increased temperature and CO₂ levels. The plants were grown at two temperature levels (26/16 °C and 29/19 °C) and four different CO₂ concentrations (400, 600, 800, and 1000 ppm). The essential oils were obtained by Clevenger apparatus and the essential oil compositions were determined using GC and GC/MS. Moreover, the concentrations of three important phenolic acid contents (mg/kg) were determined using HPLC. In the present study, it was determined that the main components of local Arapgir landrace of Turkish’s purple basil were methyl (Z)-cinnamate and linalool, and it is classified in the methyl (Z)-cinnamate/linalool group of Turkish Basil. Comparing different temperatures and CO₂ concentrations, it was determined that the temperature increased total phenylpropanoid content. However, whereas the methylcinnamate didn’t change significantly with temperature, the linalool content was found to be higher at lower temperatures. In both temperature conditions, total phenylpropanoid content was found to be the highest in control CO₂ concentration (400 ppm), and it showed regular decrease until 800 ppm. However, linalool increased regularly until 800 ppm. The highest data in rosmarinic and caffeic acids yields were obtained at lower temperatures, while there weren’t regular trends in CO₂ concentrations. In the present study, it was determined that the components of basil might change depending on the temperature and CO₂ concentrations.

Key words:

• CO₂ concentrations
• Essential oil
• Purple basil (Ocimum basilicum L.)
• phenolic compounds
• temperature