General combining ability for volume growth of open-pollinated progenies of Korean Pine (Pinus koraiensis)

Abstract

Genetic quality of plus trees selected phenotypically is generally determined by progeny tests in a breeding program. For the progeny test, there are a few limitations; all plus trees are not selected in the same year, seed collection does not occur in the same year due to flowering irregularity, unequal availability of progenies among families, and so on. Such limitations reflect spatial and temporal variation in the establishment of progeny test trials. Thus, one should develop a method of standardization in order to apply genetic information (i.e., general combining ability) from the progeny tests into genetic thinning or establishment of improved seed orchard. In this study, we developed a method for standardization to estimate general combining ability (GCA) based on the standard-site adjustment system. The method developed took the age of progeny and the number of test sites into account, which was based on the standard deviation of volume index (Height x DBH2) among different ages, sites and replications. Also, we used different weight values depending on the number of test sites and replications, and the age of trials. This method might give a general base on which to generalize the spatial and temporal variation in progeny tests. On the basis of the method, we estimated theGCA of 244 open-pollinated families of Pinus koraiensis that were tested at four sites (Gunpo, Chuncheon, Kangryuong and Chungwon)established from 1975 to 1994. Among 244 families, KW15 (0115) family showed the highest GCA value, while KW28 (0128) familyrevealed the lowest GCA value. Each family had different GCA values depending on the age of progenies as well as sites. Although there are some needs to consider on gene-ecology for accurate results, the method we reported could be useful to estimate the GCA values of progenies tested under different ages and sites.