In this study, the average yields of essential oils were
determined for both eucalyptus species. A very important difference was found
between the two returns; for the E. sideroxylon, the yield is 7 times
more than that recorded in the species E.gomphocephala. This finding of
essential oil (EO) in E. sideroxylon has been correlated to the large
oil pockets founded on both sides of the mesophyll leaf as well as the shape. As
for E. gomphocephala, the examination of the histological sections by photonic microscopy showed that oil pockets are not visualized for this species,
which confirms the low yield. The chromatographic analysis of the EO has made
it possible to separate 102 compounds, of which five have been identified and
which have about 94.58%. Among these compounds, the cineole is the majority
compound with a content of 79%. Other metabolites have been found at relatively
high levels, namely myrcene, α-terpineol, terpinolene and spathulenol. The
quantitative and qualitative difference in essential oil between the two
species studied was confirmed by the sensitivity of the different
phytopathogenic fungi to the essential oils of Eucalyptus which differs from
one species to another. Indeed, the EO of E. sideroxylon revealed very
strong inhibitory activity on Fusarium and Penicillium.
Nevertheless, the EO of E. gomphocephala has no effect on the strains of
phytopathogenic fungi tested.