Effects of Harvesting Stages, Harvesting Hours and Drying Methods on Essential Oil Content of Lemon Balm Grown in Eastern Mediterranean

Abstract

This study was conducted to determine the best harvesting stage, harvesting hours and drying method of lemon balm grown at two sites with different altitudes to obtain the highest essential oil yield. The experimental design was an Randomized Complete Block Design in a split-split plot arrangement with four replications comparing three harvesting stages (before flowering, at flowering and after flowering), three harvesting hours (6 am, 12 and 7 pm) and three drying methods (sun drying, shadow drying and fresh leaves). Essential oil content was between 0.064 and 0.073% in the lemon balm grown in Sinanli and it varied from 0.08-0.14% the lemon balm grown in Batiayaz. Essential oil content was affected from harvesting stages, harvesting hours and drying methods in both locations. When the harvesting stages were in consideration, the highest oil content was obtained before flowering in Sinanli, whereas the highest oil content was obtained after flowering in Batiayaz. The most suitable harvesting hours were in the morning (6 am) in Sinanli and in the evening (7 pm) in Batiayaz. The highest oil content was obtained from shadow drying in both locations. β-caryophllene and germacrene-d were the major volatiles, whereas, neral and geranial, the important essential oil components of lemon balm, were found in low quantities, while the other important component citronellal was not detected in the lemon balm grown in both locations.