Fertility Variation, Genetic Relatedness, and Their Impacts on Gene Diversity of Seeds From a Seed Orchard of Pinus thunbergii

Clonal differences in the number of male and female strobili were determined for five consecutive years in a clonal seed orchard of Pinus thunbergii in Korea. The effects of relatedness and clonal differences in reproductive development on gene diversity of seed (in terms of accumulated relatedness by status number) were estimated. While clonal differences were found, fertility variation was not large through all studied years. The orchard clones were divided into different regions and locations based on the geographical distribution and distance of natural stands that plus trees were selected from. Assuming that there was no relatedness among regions, locations and clones, the status number (N_s) was varied from 47.6 to 55.5 for five successive years. On average (pooling), N_s was 92% of census number (N). Assumed relatedness among regions, locations and/or clones decreased the status number. Effect of parental selection on relatedness and orchard management was also discussed.