effect of cow manure rate on essential oil content of rosa damascena mill.

the essential oil of rosa damascena mill. is one of the most valuable and important base material in the flavor and fragrance industry. the aim of this study was to determine the effects of different rates of cow manure on the essential oil of the rose petals. for this a field experiment was conducted on a clay loam soil at the research farm of alborz research station, karaj, iran. experimental design was randomized complete block design with three replications. treatments included 15, 30, 40 ton/ha cow manure and control without any manure. flower oil content was determined by distilling a representative petal sample per replication in clevenger’s apparatus. analysis of variance indicated the significant effect of treatment on percent of essential oil and yield oil in third years. the highest oil content was found on 30 t/ha (0.067%) as compared to other treatments. the essential oil yield (1102.44 g/ha) were the highest in 15 t/ha manure. . the essential oil in the third year of flowering has increased 71 percent in treatment of 15 t/ha, compared with the control. increase of more than 30 tons of manure had a negative effect on the oil yield and essential oil of rose and not advisable.