Effect of Organic and Chemical Fertilization on Qualitative and Quantitative Characteristics of Melissa officinalis (Lemon Balm)

To study the effect of bio and chemical fertilizers on quantitative and qualitative characteristics of Melissa officinalis, a greenhouse experiment was conducted during 2013 growing season at research greenhouse of Agricultural Research Organization of Qazvin, Iran. A Factorial experiment was conducted based on randomized complete block design with 18 treatments and 3 replications. Factors included: chemical fertilizer at three levels (0, 50 and 100% of current consumption); vermicompost at three levels (0, 15, 30 percent of the pot) and Biophosphate at two levels (with and without application). The results showed that vermicompost had a significant effect on morphological characteristic and essential oil content in lemon balm, so that the maximum plant height, number of branches per plant, seed weight and percentage of essential oil, were obtained by 30 % pot volume vermicompost. The maximum fresh weight (183.33 gr) was obtained by applying 30% vermicompost per pot plus biophosphate. However, the highest plant dry weight (75 gr) was occurred with the vermicompost plus chemical fertilizer. The highest amount of citronellal (47.78%) in the plant essential oil was observed in applying 30% vermicompost per pot. Chemical fertilizers also had a significant effect on the citronellal percentage, so that the use of chemical fertilizer significantly reduced the amount of citronellal. The highest percentage of geranial (19.818%) was obtained by applying 100% of current consumption of NPK. In addition, our results indicated that the combination of vermicompost and biophosphate fertilizers, improved the growth and quality of lemon balm plants.