Evaluation of genetic diversity, harvest time and drying methods in Mentha piperita L. accessions based on phytochemical traits

Mentha piperita, is a member of the Lamiaceae family commonly known as Peppermint an important medicinal plant. This plant is used as a flavoring in chewing gum, cosmetics, and pharmaceutical industries. In this research, different accessions of this plant were collected from different regions of Iran. An experiment was conducted in 2021 year based on randomized complete block design to evaluate the phytochemical traits of these accessions in the half-flowering stage in Meshginshahr climatic condition. Their essential oils were extracted in the half-flowering and full-flowering stages by using clevenger apparatus. The results showed that there were significant differences among studied traits among. There are significant differences among accessions in traits of chlorophyll a, essential oil 50 and 100 percent flowering and oven (40 0C) drying method were significant at 1% probability level. There were no significant differences among anthocyanins, flavonoids, carotenoids, essential oil 50 and 100 flowering and drying method shade. Comparison of mean traits showed that the important traits such as anthocyanins (0.93-2.37 mg/g), flavonoids (0.94-2.95 mg/g), essential oil 50 flowering and drying method shade (0.44-2.06) and essential oil 100 percent flowering and oven, (0.72-3.09) were varied among accessions. Maximum correlation was shown between Chlorophyll b and carotenoids (0.98). The Ardabil, Zanjan and Hamedan were the best superior to other accessions. Therefore, superior accessions can be used in breeding programs in order to produce better cultivars in terms of essential oil content.