Variation of Ring Width and Wood Basic Density and Early Selection of Pinus massoniana Provenances

Wood samples at 1. 3 m height were collected from 24-year-old Masson Pine(Pinus massoniana) provenance trial including 49 seed sources located at Chun’an county of Zhejiang Province to study the age effect on ring width and wood density. The results indicated that there existed significant differences in ring width and wood density of every segment except the ring width of the first 1 - 5 rings between provenances,which suggested genetic improvement of wood productivity and density could be realized by provenance selection. The variation of wood density was relatively stable with cambial ages compared to ring width among provenances and the variation of ring width was susceptible to environment. Variability in juvenile wood was 36. 71% less than that in mature wood. Pattern for the radial variation of ring width was similar for provenances in different zones,that is,the variation first increased and then decreased from pith to cambium and reached maximum in 6 - 10 rings. Pattern for the radial variation of wood density was S-type increment from the pith outward then followed by a leveling off period toward the cambium. Five superior provenances,including Hengxian, Gongcheng and Xincheng of Guangxi Province,Ruyuan of Guangdong Province,and Nanjing of Fujian Province,were selected for pulpwood according to wood density uniformity. Genetic correlation analysis between ring width and wood density suggested that provenance selection of fast radial growth would lead to low wood density in 8-year-old. The earlylate correlation analysis showed that slower growth provenance could be eliminated in 7-year-old,then growth and wood basic density could be jointly selected for wood density in 12-year-old.