3个家系落叶松木材生长轮宽度与密度径向变异OA

This study systematically analyzed the growth ring width and density profile of larch wood from three families(Larix kaempferi 3×L.gmelinii 2,L.kaempferi 5×L.olgensis 77-3,L.kaempferi 5×L.gmelinii 9)from a progeny test plantation established in 1993 at Qingshan Forest Farm,Linkou County,using the soft X-ray imaging technique.During the growth cycle,all families showed rapid decrease in growth ring width during the first 10 years and then leveled off.L.kaempferi 3×L.gmelinii 2 demonstrated the largest mean annual growth ring width,indicating the fastest growth rate.The latewood percentage exhibited an initial rapid increase in the first 10 years and then displayed a fluctuating upward trend.L.kaempferi 5×L.olgensis 77-3 showed the best stability in latewood percentage.The average earlywood density decreased slightly in the initial growth stage,increased significantly from the 6th to the 8th growth ring,and decreased again after the 15th growth ring.The average latewood density increased rapidly in the first 10 growth ring and remained stable thereafter,resulting in the average density of growth rings showing an initial increase followed by a slight decrease.L.kaempferi 3×L.gmelinii 2 exhibited the highest latewood density,while L.kaempferi 5×L.olgensis 77-3 had the lowest variation coefficients for earlywood and growth ring density,indicating superior stability between growth rings.This research provided theoretical and technical supports for selecting superior families and targeted breeding of larch.