Agronomic interventions for the improvement of essential oil content and composition of damask rose (Rosa damascena Mill.) under western Himalayas

• Effect of agronomic interventions in damask rose.
• Harvesting date significantly affected essential oil content and composition of damask rose flowers.
• Flower harvested after clear sky during previous night recorded 18% higher essential oil content (0.040%).
• Damask rose flowers can be stored up to 96 h without any significant effect on the essential oil content at 4 ± 1 °C.

Experiments were conducted during 2011–2012 to find out the effect of various agronomic interventions viz., harvesting date, harvesting conditions and storage duration of damask rose (Rosa damascena Mill.) flowers on essential oil content and composition in western Himalayas. The rose essential oil was obtained by hydro-distillation and the compositions of oil were analyzed by GC and GC–MS. The quantity was measured as the ratio of oil to rose flower (v/w%) and the quality was evaluated using the oil composition. Results revealed that harvesting date significantly affected oil content and composition of damask rose flowers. Flowers harvested on April 19 recorded significantly higher oil content (0.051%), higher citronellol + nerol (36.8 ± 2.3%), oxygenated monoterpenes (67.2%), whereas, hydrocarbon content was lowest (20.4%), which is desirable for high quality rose oil. Flower harvesting conditions also affected essential oil content and composition. Flower harvested after clear sky during previous night recorded 18% higher essential oil content (0.040%) as compared to flower harvested during rain (0.034%). The quality of the essential oil was also better. Storing rose flowers at 4 ± 1 °C did not affect the essential oil content up to 96 h. At the end of storage, essential oil content decreased by 15.7, 15.7, 11.8, and 5.9% for 240, 192, 144, and 96 h respectively as compared to control. The concentration of citronellol + nerol, main components of rose oil increased up to 96 h after storage as compared to control. However, with increasing storage time, geraniol showed remarkable decreasing trend.