Manures, vermicompost, and chemical fertilizer impacts on the yield and volatile compounds of the damask rose (Rosa damascena Mill.) flower petals

Abstract

Volatile oil from the flower petals of damask rose (Rosa damascena Mill.) is one of the most valuable and important raw materials in the perfumery, cosmetics, and pharmaceutical industries. In this study, the impacts of vermicompost, animal manures, and chemical fertilizer on the flower yield, quantity, and chemical compositions as well as the quality index of the volatile oils from the R. damascena flower petals were assessed during three experimental years (2016–2018). Results indicated that the influences of the organic manures and chemical fertilizer during three experimental years were significant on the volatile oil content and yield and the percentages of some major constituents of the volatile oil. The maximum value of the fresh flower petals weight was obtained from the vermicompost, horse dung manure, and N-P-K fertilizer in the third experimental year. In addition, chemical fertilizer treatment followed by the vermicompost and horse dung manure had the highest essential oil content in the second and third experimental years. The vermicompost, horse dung manure, and N-P-K fertilizer improved the volatile oil yield by 102.6%, 99.9%, and 107.9%, respectively in the third experimental year (2018) with control (non-amendment) in the first experimental year (2016). Furthermore, the main compounds of the R. damascena volatile oils analyzed by GC-FID and GC/MS were β-citronellol, geraniol, nonadecane, heneicosane, 1-nonadecane, E-citral (geranial), Z-citral (neral), and α-pinene, which the experimental treatments had significant impacts on their percentages. The highest concentration of monoterpene alcohols (such as β-citronellol and geraniol), as an important quality index, which contributes mainly to the perfumery value of rose oil, were obtained from the vermicompost and animal manures in the third experimental year (64.35%, 65.47%, and 61.53%; vermicompost, horse dung manure, and cow dung manure, respectively). Moreover, the best treatment for β-citronellol/geraniol (C/G) ratio, as a typical characteristic of rose oil, was the cow dung manure in the third experimental year by 1.3. On the other hand, the highest values of hydrocarbons such as heneicosane, n-nonadecane, 1-nonadecene, and docosane were obtained from control and N-P-K fertilizer in the first and second experimental years. In conclusion, to improve the quantity and quality of the damask rose volatile oil and also aromatic plant, applying organic sources such as vermicompost and animal manures are recommended in the semiarid climate.