The effect of vermicompost and nitrogen and phosphorus fertilizers on morphological and phytochemical traits of Mentha piperita L.

Biological fertilizers play a significant role in increasing the quantitative and qualitative yield of medicinal plants. In this research, the effects of vermicompost as well as nitrogen and phosphorous fertilizers were investigated on morphological traits such as height of plant and number of nod and quantitative and qualitative functions of peppermint essential oil. A factorial study was conducted as a pot experiment under the field conditions in a completely randomized design with 4 replications in 2017. Vermicompost treatment levels (consumption and non-consumption according to the manufacturer's recommendation) and nitrogen fertilizers and phosphorus (0, 50, 100, and 150 kg ha-1) were added to the  pot soils early at planting stage. The most essential components in the essential oil (more than 70%) were Alphapinene, Limonene, Izomenton, Menthol, 1, 8 Cineol, and Menton. Analysis of variations showed significant effectiveness of the treatments. Comparison of means suggested that the best treatments were application of vermicompost and nitrogen and phosphorus (100 kg. ha-1) that improved the morphological traits such as plant heights and number of nod and also the quality and quantity of essential oils. It seems that vermicompost increased morphological traits and consequently the amount and components of essential oil of the plant.