STUDY THE QUANTITATIVE AND QUALITATIVE YIELD OF LEMON BALM AS A MEDICINAL PLANT AFFECTED BY GROWTH STAGE

Abstract

Lemon balm (Melissa officinalis L.) belongs to Lamiaceae family. The most important<br><br>used parts of this valuable medicinal species are its petioles. Its flowering branches are also<br><br>being used. Its ingredients are used for treating neurological disorders, gastrointestinal and<br><br>heart diseases with neurological origin. In order to examine the essential oil yield and its<br><br>quality of lemon balm affected by different growth stages, an experiment was performed<br><br>based on a completely randomized design with five replications at the Special Crop<br><br>Laboratory, college of Agriculture, Ferdowsi University of Mashhad during year of 2012.<br><br>Leaves and branches of lemon balm were collected at three stages including before flowering,<br><br>full flowering and after that and then dried in shade. Results showed that growth stages had a<br><br>significant effect on essential oil content of lemon balm (p≤0.01). The highest essential oil<br><br>content was observed in before full flowering stage with 3.4%. The main content of essential<br><br>oil was also influenced by harvest stage; at the stage of flowering, the major essential oil<br><br>compounds for lemon balm were α-Tojon, β-Tojon and Camphor with 22.9, 15.5, and 14.1%,<br><br>respectively. Thus, due to effect of growth stages on essential oil content and their<br><br>compounds in medicinal plants such as lemon balm and in order to achieve the maximum<br><br>essential oil yield, harvesting time should be determine carefully based on their growth stage.