LAUSR

Abstract It is important to know the sources of variation in crucial characteristics of medicinal and aromatic plants for choosing the optimal harvest period. The objective of this study was to evaluate the production, contents, and chemical components of the essential oil of lemon basil, as a function of the ontogenetic and diurnal variation. Twelve harvest periods (January to December 2014) and three harvest times (8:00 am , 12:00 pm , and 5:00 pm ) were studied. The highest concentrations of essential oil occurred from January to April, when the plants were in full-flowering stage, which is associated with favorable climatic conditions and the presence of young leaves. The analysis of the essential oil identified 28 components. Citral was the major component of the essential oil of lemon basil. It was observed that the citral contents was the highest in the months of January to May during florescence stage and August to December during pre-florescence stage, regardless of harvest time. We conclude that the ontogenetic variation of lemon basil characteristics is stronger than the diurnal variation. As the experiment only spanned one year, it should be repeated to verify these findings. These findings may contribute toward optimizing the harvest period of lemon basil with respect to the amount and quality of the crop.