Abstract:

Objective: By exploring the juvenile-mature correlation and patterns of genetic variation in growth traits of open-pollinated families of Schima superba with changes of age to provide a theoretical basis for enhancing the efficiency of genetic improvement of S. superba. Method: 47 open-pollinated families of S. superba plus trees established in Fujian in 2008 were investigated,tree height and DBH were measured in the 3rd,5th and 10th years,respectively,genetic variation at different ages was analyzed to reveal the changes of genetic parameters and the phenotypic and genetic juvenile-mature correlations,and the stability of increment of different families was preliminarily evaluated. Result: At different ages,the height and DBH of open-pollinated families of S. superba plus trees were significantly different from each other,and the family effect increased with the increase of age,and there was significant provenance effect. The growth of height and DBH was larger at younger age,and the growth rate of the DBH was relatively greater than that of the tree height. The growth analysis of typical families showed an unchanged trend of the early dominant and inferior families with the increase of age,while the middle families tended to become better or worse. The family and individual heritabilities of the tree height were between 0.23-0.59 and 0.09-0.56,respectively,and the family and individual heritabilities of the DBH were between 0.39-0.76 and 0.18-0.70,respectively. The genetic control of tree height and DBH were increased with the increase of age,higher level of genetic control appeared after 5 years,and the genetic control was greater in DBH than in tree height. The phenotypic variation coefficients were greater than the genetic variation coefficients of tree height and DBH; With increasing age,the genetic variation coefficient of DBH increased,and the phenotypic variation coefficients of DBH decreased,while the phenotypic and genetic variation coefficients of tree height increased first and followed by a decrease. The phenotypic and genetic variation coefficients of DBH were greater than tree height. The juvenile-mature phenotypic and genetic correlation coefficients of tree height were between 0.20-0.28 and 0.26-0.55,respectively,and the DBH was between 0.23-0.59 and 0.53-0.80,displaying a trend of increase with age,the juvenile-mature correlation was mainly controlled by genetic factors; At 5 years,the phenotypic and genetic juvenile-mature correlation of both tree height and DBH were greater than those at 3 years,indicating that early selection was more effective at 5 years than at 3 years; The juvenile-mature correlation coefficient of DBH was greater than tree height,indicating that DBH was better as an early selection trait. Based on genotype grouping,47 families were divided into 4 categories with DBH as the evaluation indicator,among them,the families with low increment and high stability accounted for the largest proportion (34.04%); 12 families such as JO49,JO62 and LQ1 were selected with the goal of high growth and high stability. Conclusion: The genetic effect of growth traits among the open-pollinated families of S. superba plus trees were increased with age increase,and there was a significant effect of provenance,families should be selected within superior provenances. The genetic control of tree height and DBH becomes higher after 5 years,and the DBH has a greater genetic control and a stronger variability than the tree height has. Juvenile-mature correlation of tree height and DBH was mainly controlled by genetic factors,DBH was more reliable as an early selection trait. DBH as early selective trait selection was more efficient at 5 years than at 3 years.

Key words: Schima superba, open-pollinated family, growth traits, genetic variation, juvenile-mature correlation