EFFECT OF APPLYING DIFFERENT LEVELS OF NITROGEN FERTILIZER ON GROWTH AND ESSENTIAL OIL OF SPEARMINT (MENTHA SPICATA L.)

Spearmint (Mentha spicata L.) is a critically important herb across the globe, with rising demand for greenhouse culture; nevertheless, little information is known concerning spearmint reactions to nitrogen addition. In a controlled environment in Iraq, the influence of different nitrogen fertilizer levels (0, 20, 40, 60, 80, and 100 kg N/ha) on the morphological characteristics and essential oil (EO) output of spearmint was investigated. With nitrogen fertilizer treatments, spearmint's leaf chlorophyll content (SPAD), agronomic characteristics, and essential oil output rose dramatically. The findings suggested that maintaining a nitrogen content of 60 kg N/ha boosted spearmint's various agronomic features and essential oil output. Nitrogen application boosted spearmint chlorophyll content, while the control treatment had the lowest chlorophyll level (without N application). Nitrogen fertilizer applications at 60 and 80 kilogram/ha improved essential oil output and percentage of essential oil, suggesting that commercial native spearmint plants should get 60 kg N/ha. In conclusion, the amount of nitrogen applied may have an influence on spearmint's vegetative growth and development, as well as on the generation of essential oils when cultivated in a greenhouse.