Essential oil is one of the most important natural products of damask rose petals (Rosa damascena Mill.). The presence of higher concentrations of aromatic compounds (β-citronellol and geraniol) in the damask rose essential oil indicates an important quality and standard indicator that foliar spraying may be effective in promoting this effective substance. The aim of this study was to evaluate the effect of alcoholic and ketone foliar application on the chemical composition of R. damascena essential oil during 2017-2018 and 2018-2019 in a completely randomized design in a rose garden located in the south of Shahrekord, southwestern Iran. The essential oil obtained by hydro-distillation was analyzed using GC/MS. In this regard, 29 compounds were identified in the essential oil, the most important of which were β-citronellol and geraniol (alcoholic monoterpenes) and henicosan and nonadcan (alkane hydrocarbons). The results indicated that the best foliar treatment was 20% ethanol solution during two experimental years; the highest levels of β-citronellol (33%) and geraniol (18%) were obtained from the ethanol spraying (at 20%) compared to other treatments and controls. In addition, this treatment was at the lowest level in terms of the concentration of alkane hydrocarbons in essential oil as a negative indicator of aromatic compounds of the rose essential oil. The acetone foliar spraying had the highest amount of alkane hydrocarbons and the lowest percentage of aromatic compounds compared to control and other treatments. In correlation's Pearson coefficients analysis, the highest significant positive correlation was obtained between aromatic compounds (alcoholic monoterpenes) with each other and between alkane hydrocarbons, meanwhile negative and significant relationships were observed between these two groups of important compounds in the rose essential oil. Finally, it is suggested that to obtain the highest quality of the R. damascena essential oil under similar climatic conditions (cold and semi-arid), the ethanol foliar application with a concentration of 20% can be useful.
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