The CAMCORE international provenance/progeny trials of Gmelina arborea: genetic parameters and potential gain
2004
Hodge, G.R. | Dvorak, W.S.
This paper reports early results from the provenance/progeny trials in Colombia, Costa Rica, Guatemala, Indonesia, Mexico and Venezuela. These were the first international collections of gmelina that were by mother tree and also the first ever to be made in Myanmar. Collections were made from 440 mother trees in 22 provenances (20 trees per provenance), while for eight provenances, bulk seed collections were made, typically from 20 trees. In this study, results from 31 tests planted in six countries are reported. At all ages, single-site heritability estimates for height, DBH, and volume were moderately low, around h(b)2 =0.10. The proportion of provenance variation ranged from p(b)2 =0.05-0.13, and averaged around 0.10. These levels are somewhat higher than has been observed for other forest tree species. Strong age-age additive genetic correlations were found for all growth traits and all age combinations. There was relatively little GxE at the provenance level (r(Bg)=0.73), and relatively substantial GxE at the family (i.e., additive genetic) level (r(Bg)=0.40). Three provenances from Thailand all were below average for 2-year/3-year volume (mean BLUP=-16.3%). These three sources were among the lowest latitude sources (below 15°N) in the study. Indian provenances ranged widely in growth performance. Of the 10 provenances from Myanmar, only two were below average. There is sufficient genetic variability to make good gains in breeding. Gain in 2-year/3-year volume from provenance selection should be on the order of +10%, and expected gain from selection of the best genotypes within provenance (e.g., the top 5%) should be on the order of +25%.
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