Effect of Different Nitrogen Doses on Agricultural and Quality Characteristics of Mentha x piperita L. and Mentha spicata L. Species

The effect of various amounts of nitrogen (N) fertilizer (0, 50, 100, 150 and 200 kg ha^-1) on the growth and quality characteristics of Mentha x piperita and Mentha spicata species was studied under Turkey’s Uşak ecological conditions in 2017-2019. In the study, harvests in the vegetation period of 2018 and 2019 were combined and the average plant height and essential oil content, total fresh and dry herbage, dry leaf and essential oil yields, and the composition of the essential oil was examined. The plant height, total yields and essential oil content of both mint species increased significantly with N fertilizer applications. The highest total yields and essential oil contents in both mint species were obtained from 200 kg N ha^-1. The main components of the essential oil were identified as menthol and menthon in Mentha x piperita and carvone and limonene in Mentha spicata. The highest menthol content (44.66%) was obtained from 100 kg N ha^-1, while the highest carvone content (59.90%) was obtained from 200 kg N ha^-1. The total yields of Mentha x piperita increased significantly with increase in N fertilization up to 200 kg ha^-1, while the total yields of Mentha spicata increased with increase in N fertilization up to 150 kg ha^-1.