From parental species E. camaldulensis, E. grandis and E. tereticornis we have studied the effect of crossing and reciprocal crossing on yield and chemical composition of essential oils of eucalyptus hybrids. The E. camaldulensis, E. grandis and E. tereticornis yields were respectively 1, 0.37 and 0.82%. The hybrid E. grandis (female) x E camaldulensis (male) give an average yield of about 0.8% against 0.7% for his reciprocal crossing. The eucalyptus hybrid E. tereticornis x E. camaldulensis yield is about 0.9%, the reciprocal crossing yield is about 0.84%. The alpha-pinene, p-cymene and 1,8-cineole are principal compounds of these essential oils. The percentage of these products vary according to parentals species and the crossing sens. These values take often intermediate values compared to parental species, but not higher than those of the parents. The results on chemical composition from different samples are discussed. However, no combination attains a sufficient content of 1,8-cineole to fit to the usual norm.
