| Cunninghamia lanceolata is an important native fast-growing plantation timber tree in Guangxi,which is widely planted in the north,northwest and northeast of Guangxi.In order to achieve the goal of fast-growing,high-yield and high-quality cultivation of C.lanceolata plantation,researchers have carried out a lot of research on genetic improvement of C.lanceolata in Guangxi,and achieved remarkable results.At present,the breeding work of C.lanceolata in Fujian,Hunan and other provinces has entered the stage of the 3rd generation seed orchard.However,Guangxi is still in the 2nd generation seed orchard stage.The effective way to improve the level of improved seed production and promote genetic improvement of C.lanceolata in Guangxi is to fully tap the production potential of improved varieties in the 2nd generation seed orchard of C.lanceolata,or to introduce excellent germplasm resources from other provinces.In this study,the progeny test forests of the 2nd generation seed orchard half-sib families in Xishan Forest Farm of Rong’an County and the 3rd generation seed orchard half-sib families introduced from Fujian Province of C.lanceolate were selected as the research objects.Statistical analysis was carried out on the growth of C.lanceolata at 2,3,4 and 5 years,and the superior families and the superior individual plants were selected,so as to provide reference for the efficient breeding,high generation breeding and genetic improvement of C.lanceolata.The results showed that:1.The preservation rate of the 2nd generation C.lanceolata test forest at2～5 years was 64.29%～100%,and 72.41%of the families were higher than the control mean.Most of the difference of plant height and wood volume between different families was significant or extremely significant.The variation coefficients of plant height,breast diameter and wood volume of the 2nd generation C.lanceolata test forest were 11.58%～17.35%,13.59%～35.26%and39.48%～52.14%,respectively,and the heritability were 0.230～0.584,0.110～0.505 and 0.420～0.451,respectively.The families whose plant height,breast diameter and wood volume were higher than the control mean accounted for 55.17%～79.31%,51.72%～82.76%and 72.41%～75.86%,respectively.For the 4 families(liu234,qingmingshan 9,liu228 and Ziliu 224)whose overall gain was 15.00%higher than the control,the average values of plant height,breast diameter and wood volume at 5 years were 5.79 m,9.02 cm and 0.02229 m~3,respectively,and the average genetic gains were 8.09%,6.83%and 29.94%,respectively.For the 23 superior individuals whose overall gain was 50.0%higher than the control,the average values of plant height,breast diameter and wood volume at 5 years were 6.7 m,13.2 cm and 0.04796 m~3,respectively.2.The preservation rate of the 3nd generation C.lanceolata test forest at2～5 years was 68.57%～100%,and 71.43%of the families were higher than the control mean.Most of the difference of plant height and wood volume between different families was significant or extremely significant.The variation coefficients of plant height,breast diameter and wood volume of the 3nd generation C.lanceolata experimental forest were 13.64%～19.13%,18.11%～33.70%and 43.56%～73.21%,respectively,and the heritability were0.197～0.589,0.247～0.493 and 0.336～0.567,respectively.The families whose plant height,breast diameter and wood volume were higher than the control mean accounted for 57.14%～73.02%,58.73%～77.78%and 55.56%～76.19%,respectively.For the 10 families(16,21,28,42,45,48,64,68,81 and 85)whose overall gain was 15.00%higher than the control,the average values of plant height,breast diameter and wood volume at 5 years were 5.74 m,8.77 cm,0.02109 m~3,respectively,and the average genetic gains were 8.17%,8.62%and28.99%,respectively.For the 27 superior individuals whose overall gain was60.0%higher than the control,the average values of plant height,breast diameter and wood volume at 5 years were 7.98 m,12.68 cm and 0.05455 m~3,respectively.3.The average preservation rate of the 3rd generation half-sib progeny forest(87.98%～91.11%)was slightly higher than that of the 2nd generation(84.62%～91.00%).The variation coefficient of growth traits of the 3rd generation of experimental forest was higher than that of the 2nd generation.The cumulative growth and the average annual growth of breast diameter and wood volume of the two test forests increased steadily with the growth of forest age.And the cumulative growth and the average annual growth of plant height,breast diameter and wood volume of the 2nd generation test forest were slightly higher than those of the 3rd generation test forests.The family heritability and family genetic gain of breast diameter and wood volume of the 3rd generation test forest was higher than that of the 2nd generation.In conclusion,the half-sib progenies of the 2nd generation seed orchard of C.lanceolata in Guangxi and the 3rd generation seed orchard of C.lanceolate from Fujian Province in Xishan Forest Farm had good growth performance in the early stage.The genetic variation of the tested families was rich,and the main growth traits were controlled by the medium or lower middle genetic control.The superior families and superior individual plants selected had excellent performance and obvious genetic gain at 5-year-old,which can be used as the construction material of high generation breeding and the 3rd generation seed orchard of C.lanceolata in Guangxi.In addition,in the future,we could give priority to the germplasm resources of the native seed orchard in Guangxi,and appropriately introduce superior germplasm from other places to supplement the breeding population of C.lanceolata and enrich the genetic diversity of C.lanceolata breeding in Guangxi. |
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