Diallel crossing in Pinus cembra : IV. Age trends in genetic parameters and genetic gain for growth and branching traits

This paper reports results from a complete 10 x 10 diallel carried out in a natural population of Swiss stone pine (Pinus cembra L.) from the southern Carpathian Mountains. At age six, after nursery testing, the material was field planted on one site, using a completely randomized block design with 100 families, fourreplicates and 15 tree row-plots per replication, spaced 2.5 x 2.5m. Total and annual height growth, root collar diameter, number of branches per whorl and survival were assessed at successive ages between ages eight and 14 after seed. In addition, severaltraits that were assessed during the nursery test were used in correlation and some other analysis. Plot means of the measured traits were analyzed using the general least-squares method by means of the computer DIALL programme prepared by Schaffer and Usanis (1969). Across the field testing periods, significant (p<0.05) andhighly significant (p<0.01; p