Effect of Vermicompost and Nitrogen Fertilizers on Morphological Traits, Percentage and Essential Oil Yield of Melissa Officinalis

In order to study the effect of organic (vermicompost) and chemical (nitrogen) fertilizers on the quantitative and qualitative yield of Melissa Officinalis, a factorial experiment was conducted based on randomized complete block Design (RCBD) with three replications in the Research Field of Golestan Research and Training Center of Agriculture and Natural Resources. Experimental factors included vermicompost at four levels (0, 2.5, 5, and 7.5 tons ha-1) and urea fertilizer with 46% nitrogen at four levels (0, 50, 100, and 150 kg ha-1). Results showed that vermicompost had a significant effect on morphological characteristics and percentage of essential oil of Melissa Officinalis. The highest plant height, number of branches, leaf length and width, fresh weight, dry weight, and percentage of essential oil was obtained in application of 7.5 ton/ha vermicompost. Also, there was a significant difference between different levels of urea fertilizer so that the percentage of essential oil significantly increased when the fertilizer was applied. The highest amount of essential oil (0.49%) was obtained in simultaneous application of vermicompost (7.5 tons ha-1) and nitrogen fertilizer (100 kg ha-1) which was 38% higher than control. In general, the results showed that application of vermicompost with nitrogen increases shoot growth and dry matter production, ultimately increases the yield quantity, and significantly improves the yield of Melissa Officinalis essential oil.