Productivity and essential oil quality of Dracocephalum kotschyi under organic and chemical fertilization conditions: Biomass production and essential oil compositions of Dracocephalum kotschyi

Organic manures play an important role in the growth and biomass of aromatic and medicinal plants leading to organic and cleaner production. Also, organic manures can improve chemical compositions and the quality of aromatic and medicinal plants. Hence, a field experiment was conducted to study the usage of organic manures and inorganic fertilizers on biomass, essential oil content, essential oil yield and chemical compositions of Dracocephalum kotschyi Bioss (D. kotschyi) in the first and second cuttings. The treatments consisted of: broiler litter, cow manure, sheep manure, chemical fertilizer and the control (without fertilizer). The results showed that the highest aboveground biomass and essential oil yield of D. kotschyi was obtained in plants treated with broiler litter in both cuttings. All treatments in the second cutting showed higher aboveground biomass and essential oil yield as compared with the first cutting. Plants amended with broiler litter and sheep manure had the highest essential oil content in the first and second cuttings, respectively. Neral, geranial, geranyl acetate and α-pinene were major chemical compounds of D. kotschyi in both cuttings. At the first cutting, the maximum content of neral (28.24%) and geranial (26.85%) were recorded in plants treated with sheep manure and chemical fertilizer, respectively. In the first cutting, the greatest α-pinene content (15.52%) was achieved in the control treatment that had insignificant difference with the broiler litter. Unlike the first cutting, plants amended with cow manure had maximum content of neral (23.89%) and geranial (29.27%) content upon the second cutting. The present study indicated that the usage of organic manures by improving of photosynthetic conditions and increasing of biomass lead to improve the quality and aroma profile of D. kotschyi. © 2020 Elsevier Ltd