Effect of Nutrients on Drug Production and Essential Oil Content of Lemon Balm (Melissa officinalis L.)

Nutrient supply of several medicinal plants is often carried out according to empirical knowledge without proper data on specific requirements. In a recent three years (2009-2011) open field experiment in Budapest, Hungary we examined the effects of different fertilizers on biomass, drug yield and essential oil content of lemon balm (Melissa officinalis L.). In general, effects of the treatments were more pronounced on the results of the second harvest than that of the first one. The treatment with 150kg/ha N+22kg/ha P supplemented by 36kg/ha Mg resulted in 25-27 % higher folium mass compared to both untreated and N+P treated plots. Similarly, supplementary dosages of 36kg/ha Mg+149kg/ha K assured by 24 % more folium yield compared to untreated and 10 % more yield compared to N+P fertilized control. In some cases decreased leaf proportion parallel with enhanced yields could be observed. The best fertilization treatments assuring highest yield, tend to produce a slight decrease in essential oil content of the leaves of the second harvest but still an appropriate drug quality due to Ph.Eur.