THE USE OF SELF-INCOMPATIBILITY IN THE PRODUCTION OF HYBRID EUCALYPTUS SEED BY ARACRUZ-CELULOSE IN BRAZIL

Self-incompatibility found in a Eucalyptus grandis clone was used to p romote interspecific hybridization between E. grandis and E. urophylla clones. The interspecific hybridization achieved in an open-pollinate d commercial seed orchard planted in Espirito Santo, Brazil was evalua ted by the multi-locus outcrossing rate (t(m)) Of the seed producing c lone, E. grandis. The percentage of outcrossed seeds reached 95.9%. Th e outcrossing rate of individual trees was quite variable, but was alw ays above 70.0%. Wright's coefficient was negative (F = -0.30) reveali ng an excess of heterozygous genotypes in the progeny. Genetic paramet ers confirmed the high degree of hybridization expected in this orchar d. The 800-m wide protection belt of native tropical forest that surro unds this orchard has significantly reduced pollen contamination, in c omparison to a 400-m wide belt used in another local seed orchard.