Effects of Top-Pruning Time on Fresh Flower Yield, Rose Oil Content and Compounds in Oil-Bearing Rose (Rosa damascena Mill.)

Abstract

The aim of the research was to determine the effects of top-pruning time on flower yield, rose oil content and oil constituents in oil-bearing rose. Five-year old rose plants were top-pruned in three different dates starting from 15 March (early), 30 March (middle) and ending 15 April (late) before they started new growth in spring. In addition, non-pruned (untreated) parcels were used as controls. Top pruning time significantly affected the flower yield, oil content and its constituents. The highest flower yield (4302 kg/ha) was obtained from non-pruned plants. The fresh flower yield and rose oil content increased significantly from 3559 kg/ha to 3905 kg/ha and from 0.030 % to 0.045 %, respectively when the pruning time was delayed. GC-FID/MS analyses of rose oils revealed that monoterpenic constituents, such as geraniol and citronellol were higher in the rose oils distilled from late-pruned plants, paraffinic hydrocarbones (stearoptenes), such as nonadecane and heneicosane were higher in the rose oils distilled from early-pruned plants. The mid- pruning time (30 March) gave the highest citronellol and geraniol by 27.28 % and 30.64 %, respectively. A remarkable result was that methyl eugenol content, which is not desirable above a spesific quantity in rose oil due to allergic effects and mutagenic, decreased from early to late pruning.