Arrays of open-pollinated seeds were assayed for allozyme polymorphisms at three loci (Adh, Gdh, and Mdh-2) to obtain a quantitative estimate of outcrossing rate in a seed-production area of Eucalyptuscitriodora (Hook). Rate of outcrossing varied among loci, but suggested overall that up to 14.7% of the seed might be derived from self-fertilization at the viable embryo stage. Such a level of partial self-fertilization, together with local variation in the mating system, yielded an observed average inbreeding coefficient of 0.205 for these loci in the progeny arrays. By contrast, the mature trees exhibited substantial excesses of heterozygotes (F = −0.300), concordant with but not necessarily supportive of earlier hypotheses that selection against homozygotes through the life cycle occurred in eucalypts.

To identify stable and productive Eucalyptus urophylla S.T. Blake families across diverse climate zones in Brazil, we evaluated growth and survival of 322 open-pollinated families derived from 13 genetically improved seed sources in 10 trials across the country. Survival and growth data were analyzed using linear mixed models and REML/BLUP. Survival ranged from 51% to 92%, and the mean annual increment varied from 19 to 46 m3·ha−1·year−1. Although planted in suitable climatic zones, some trials had low survival and (or) productivity. Conversely, the highest productivity was recorded in a zone considered to be of low suitability. These results show the importance of assessing the climatic requirements of eucalypts beyond those determined from analyses of their natural distribution, especially when testing already improved seed sources. A number of productive and stable families were identified based on analysis of the interaction between genotype and environment, and from these, 144 individuals were selected and had their genetic diversity estimated using 19 microsatellite DNA markers. The genetic diversity of these selected trees was equivalent to that observed in previous studies of natural populations of E. urophylla, indicating that breeding programs of E. urophylla in Brazil still retain high levels of diversity for sustainable genetic gains.

Our aim was to verify the effect on gain and genetic diversity through the restriction of the number of trees per family in selection, in order to compose an elite population of Eucalyptus urophylla in two trials under distinct management levels.We studied 166 open-pollinated families of E. urophylla in Anhembi, Sao Paulo State, Brazil under commercial practices, and the same families in Selvíria, Mato Grosso do Sul State, Brazil under lower management level (mainly no mineral fertilization). Mortality, height and diameter at breast height (DBH) were measured. DBH was analyzed by the REML/BLUP to select the best 25 trees, with four levels of tree restriction per family (no restriction; 1; 2 and 3 per family). We evaluated heritability; genetic gain and effective size of number of total and private alleles; observed and expected heterozygosity; coancestry and fixation index. A large difference in survival (48 and 83 %) and productivity (MAI of 26 and 44 m 3 ha -1 y -1 ) was observed between trials due to the different levels of management applied. The highest restriction in number of individuals per family caused a small decrease in gain, corresponding to 7 % in the more productive trial and 3 % in the less productive one. Observed and expected heterozygosity, coancestry and fixation index were not significantly (lower than 5 %) affected by the restriction in both sites. The restriction of one tree per family allowed different alleles to be kept in the selected population and higher effective population size in order to insure variation for the next generations. Maintenance of genetic diversity in Eucalyptus urophylla S. T. Blake populations with restriction of the number of trees per family

Eucalypt species are widely used around the world due to their high productivity; however there are some concerns about the invasiveness capacity of eucalypts. We assessed old seed production areas of commercial eucalypt species thought of being at risk of invasion in two places in Southeastern Brazil (Anhembi: lat: 22°28 0 S; long: 48°04 0 W; and Itatinga lat: 23°02 0 S; long: 48°38 0 W). We observed differences between places and among species. The species with the higher number of plantation stands and higher demand for seeds had more regeneration. Regeneration was recorded in only a few plots and trees and seedlings were found very close to the eucalypt stand, in sites where waste from seed harvesting is dumped. For spontaneous regeneration of eucalypts to occur there is a need for favorable environmental conditions. Such conditions may be created by human activities or natural events which suppress competition from vegetation.

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