Biomorphological features and harvesting time in Mentha piperita L. varieties of different designation

In the conditions of Moscow district the authors studied the biomorphological and economical valuable determinants in 10 varieties of Mentha piperita L. The indices of rhizome germinative energy, the duration of vegetation period, the winter hardiness of varieties, the resistance to main disease (powdery mildew, causative agent Erysiphe communis ) were established, the productivity and quality of raw material were estimated. The optimal harvesting time for varieties of different special designation was studied. The harvesting at the bud-formation period of the mint varieties from first group (Medichka, Lekarstvennaya 4, Chernolistnaya, Krasnodarskaya 2 and Prilukskaya 6) permits to obtain high yield of pharmaceutical leaf (1.37-1.81 tonne per hectare) with good commercial quality. The optimal harvesting time for varieties from second group (Moskvichka, Yantarnaya, Kubanskaya 6, Tundzha, Zgadka), which are growing for making essential oil and menthol, is the phase of mass flowering, that promotes to yield of essential oil of 43.0-65.7 kg per hectare.