Plus Tree Selection of Quercus salicina Blume and Q. glauca Thunb. and Its Implications in Evergreen Oaks Breeding in Korea

Abstract

This study was conducted to select plus trees of two evergreen oaks, Quercus salicina and Q. glauca, in Korea. Evergreen oaks are distributed in subtropical region in Korea and have recently emerged as one of the alternative tree species against climate change. Accordingly, a tree breeding program is underway to foster evergreen oaks as a reforestation species for the future. Through intensive survey on the distribution range, 15 stands (8 for Q. salicina, 3 for Q. glauca, and 4 for both species) were selected as base populations. To select candidate trees, we developed a subjective grading system with six characteristics in three categories and introduced a weighted generalized value (GVIw) to compare superiority of candidate trees. The candidate trees were screened using baseline value ‘0’, i.e., if GVIw > 0, then accepted and if GVIw < 0, then rejected. After then, adjustment was conducted to avoid biasing the selection of plus trees for a particular location. Through this process, 44 candidate trees in Q. salicina and 41 candidate trees in Q. glauca were selected as plus trees. Finally, the results and implications were discussed in relation to evergreen oak breeding in Korea.

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