Genetic Analysis Of Eucalyptus Hybrid Progeny Obtained By Nest-Mode Mating Desingn

The study trial was established in Dongmen Forest Farm using eucalypt hybrid seedlings. The hybrid seeds were obtained by artificial pollination with nest-mode mating design where15eucalypt clones from a dwarfed seed orchard were selected as female parents and21eucalypt families from a1st generation seed orchard were selected as male parents.2.5years after planting, trees of the trial were selected and their growth traits including diameter at breast height (DBH), tree height (Ht) and individual volume were estimated. Their genetic variation and heritability among hybrid combinations, and the genetic correlations and combining ability among growth traits were analyzed. Superior hybrid progenies were screened. The study results are showed as the followings:1. The30hybrid combinations were clustered into4groups (including fast-growing, medium-growing, normal and slow-growing group) using analysis of system clustering method. Mean individual volume of the hybrid combinations from fast-growing group was37.07%higher than that of the whole tested population,8.48%higher than CK2, and4.83%lower than CK1.2. The differences between maternal and paternal effects on DBH were not significant. Compared with maternal effect, paternal effect had more impact on tree height and individual volume, with47.63%maternal effect and52.37%paternal effect on tree height, with45.9%maternal effect and54.1%paternal effect on individual volume.3. Family heritability and individual heritability were more than68%, which showed that growth traits were mainly controlled by genes. They were also affected by environmental conditions to some extent. Maternal family heritability, paternal family heritability and full-sibs family heritability of individual volume were lower than those individual heritabilities. 4. Compared with tree height, DBH had a stronger correlation with individual volume.5. Female parent DH33-27had the largest individual volume and its general combining ability (GCA) was up to0.011. On the other side, female parent DH206-1had the smallest individual volume and its GCA was-0.01048. When the volume was taken as the breeding goal, DH33-27should be firstly selected in hybrid designs.6. For all traits within a combination, there were13combinations with all traits showing positive values within each of them. So, these combinations would be the ideal ones for hybrid.7. Taken individual volume as a selecting indicator, clone DH32-28(CK1) and GL-9(CK2) as control, three combinations, namely DH33-27xT84, DH107-1×G351and DH83-1×G344, were chosen as the best according to their greater GCA and SCA values. Finally,11strains were screened in the optimal combination of trees,18strains were screened in combination with other non preferred tree.