Effects of harvest stage and diurnal variability on yield and essential oil content in Mentha × piperita L.

This study aimed at investigating the effect of ontogenetic and diurnal variability on yield quality criteria Mentha piperita. The research was conducted in Ordu province Turkey for two years. trial established a randomised complete block design with 3 replications according to factorial regulations. Four different harvesting periods (budding, first flowering, 50% 100% flowering) three hours (9:00 a.m., 1:00 p.m., 5:00 p.m.) were evaluated. A significant difference determined between years all characters examined: plant height 55.9–69.0 cm, fresh herb 236–16 438 kg/ha, drug-herb 1 748–2 862 leaf 477–4 506 drug 968–1 253 essential oil ratio 2.0–2.5% that varied 19–28 L/ha. highest yields obtained beginning flowering period other characteristics. Diurnal statistically only rate oil, occurred 9:00 a.m. harvest.