2019, Vol. 7, Issue 3, Part B

author(s)
Fikremariam HD, Dagnew YW, Degnechew GD and Tesfaye BA

abstract
The aim of this study is to investigate the influence of two experimental factors: Tree ages of (2, 3, 4, 5, 6, 7 and 8 years) and growing locations (i.e. Entoto, Fiche, Debresina and Jida) on Essential oil content (EOC) and Essential oil yield (EOY) of Eucalyptus globulus leaves. The experiment was carried out to determine the Moisture content (MC), Essential Oil Content (EOC) and Essential Oil Yield (EOY) which were expressed by MC (%), EOC (%) and EOY (kg/ha) basis of dry leaf weight. The oil was extracted by hydro distillation from E. globulus leaves using Clevenger apparatus for 3hr. The MC, EOC and EOY were highly significantly (p ≤ 0.0001) affected by the experimental factors: tree ages, its growing locations and their corresponding interactions. It has been observed that in case of crossways at all locations the mean maximum value of MC was recorded as 52.57% on tree of age 5 and minimum 42.02% on tree of age 8. Moreover, the mean value of EOC content has revealed significantly higher value for leaves of age 4 (2.49%) and leaves of age 6 (2.5%), followed by leaves of age 5 (2.39%). The least EOC content was recorded for leaves of age 8 (1.84%), which yielded 26.4% lower than the maximum. The mean maximum value of EOY was also obtained from leaves of age 6 (4254 kg ha ^-1) in Fiche, and the next higher value of EOY was recorded on leaves of age 8 (2666 kg ha ^-1) and leaves of age 2 (2674 kg ha ^-1), respectively at the same growing site. The crossways at all growing sites per age on mean values of EOY content has shown that significantly higher value for leaves of ages 6 (1643.75 kg ha ^-1) and leaves of age 2 (1711.38 kg ha ^-1). The least value of EOY was recorded for leaves of age 3 (1045.50 kg ha ^-1), which yielded 38.91% lower than the maximum value. Therefore, it can be concluded that tree leaves of age 6, which was grown at Entoto have significantly high EOC with value of 3.89% in dry biomass (DB) than matured tree leaves of ages 7 and 8, which were grown at Fiche, Debresina and Jida. The tree leaves of age 6, which was grown at Fiche have had significantly high EOY with value of 4254 kg ha ^-1 in dry biomass (DB) than young leaves of ages 2-5, which were grown at Entoto, Debresina and Jida.