Copious shoots as a potential source for the production of essential oil in Eucalyptus globulus

Eucalyptus globulus Labill. (Myrtaceae) is a commercially important natural resource mainly used by pulp and paper industry due to its higher quality cellulosic fibres and for the production of medicinally important essential oil. After the coppicing of trees for the former use, it is not used by the essential oil industries for a long time resulting in a loss of economy. Based on this fact, an attempt has been made to practice its simultaneous use for the two different sectors. Variation in the essential oil yield and composition from leaves of both, before and after coppiced trees has been qualitatively analyzed throughout the year in different seasons by GC-FID and GC–MS. A total of twenty-eight constituents representing 98.4–99.3% from before and twenty nine volatiles representing 97.5–99.5% of the total essential oils composition after coppicing were identified. The essential oil yield ranged from 1.6% to 1.9% before and 1.7% to 2.1% after coppicing. Moreover, the principal component, 1,8-cineole was present significantly (p ≤ 0.001) higher in essential oil of copious shoots (81.7–85.8%) than non coppiced crops (63.1–68.3%). In respect to seasonal variation, the oxygenated monoterpenes (74.9 and 90.8%) was the dominating class during winters while sesquiterpene hydrocarbons and oxygenated sesquiterpene were at their peak during the rainy season (17.0 and 10.8%; 3.4 and 6.0%) in both the cases. Comparative results showed considerable variations in the essential oils composition from before and after coppicing as well as during the seasons. The study concluded that essential oil producers can keep the higher and 1,8-cineole enriched essential oil from copious shoots into consideration for valorization of this natural resource which can be economically practicable, especially if considered as a compliment of pulp production.

► Yield and quality of essential oil of Eucalyptus globulus leaves, before and after coppicing of tree, were compared in different seasons.
► Leaves of copious shoots produced higher oil yield with enhanced cineole content.
► Seasonal variation pattern remained same in both the cases with superior quality oil in winters.
► Method is economically practicable and compliments the pulp production.