Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Genetic control of the time of transition from juvenile to mature wood in Pinus radiata D. Don. | Ann. For. Sci. 63 2006 871-878 INRA EDP Sciences 2006 DOI forest 2006070 871 Original article Genetic control of the time of transition from juvenile to mature wood in Pinus radiata D. Don Washington J. Gapare Harry X. Wu Aljoy Abarquez Ensis Genetics PO Box E4008 Canberra ACT 2604 Australia Received 14 February 2006 accepted 30 May 2006 Abstract - The success of selective breeding for growth rate and subsequent reduction in rotation age in Pinus radiata has resulted in almost 40 of the log constituting juvenile wood in some cases. Juvenile wood properties in radiata pine are known to be limiting in factors such as low density spiral grain fibre length and compression wood. Juvenile wood quality may be improved by breeding for increased stiffness of juvenile wood or an early transition age from juvenile to mature wood. The objective of this study was to investigate the age of transition from juvenile to mature wood and quantify genetic control in time of transition from juvenile to mature wood using 1866 radiata pine samples. Wood samples from two 16-year-old Australia-Wide Diallel AWD radiata pine tests and two 28-year-old open-pollinated OP progeny tests were submitted to X-ray densitometry procedures. An important finding of this study is the site difference in latewood density transition-age between tests at Flynn and Silver Creek in Gippsland Victoria mean y and at Tantanoola in Green Triangle South Australia mean y . This finding suggests that site has a major effect on juvenile-mature transition in radiata pine. We detected moderate levels of genetic control in latewood density transition age that would allow for selective breeding for a shorter juvenile wood formation phase. These results suggest that there may be an opportunity to select for a reduction in transition age and therefore increase the overall wood uniformity. Pinus radiata juvenile wood mature wood transition age heritability Résumé - Contrôle génétique de l âge de transition
