Self-incompatibility found in a Eucalyptus grandis clone was used to promote interspecific hybridization between E. grandis and E. urophylla clones. The interspecific hybridization achieved in an open-pollinated commercial seed orchard planted in Espírito Santo, Brazil was evaluated by the multi-locus outcrossing rate (tm) of the seed producing clone, E. grandis. The percentage of outcrossed seeds reached 95.9%. The outcrossing rate of individual trees was quite variable, but was always above 70.0%. Wright's coefficient was negative (F = -0.30) revealing an excess of heterozygous genotypes in the progeny. Genetic parameters confirmed the high degree of hybridization expected in this orchard. The 800-m wide protection belt of native tropical forest that surrounds this orchard has significantly reduced pollen contamination, in comparison to a 400-m wide belt used in another local seed orchard.
