Clonal Contribution and Sexual Asymmetry based on Flowering Assessment in Two Clone Banks of Pinus koraiensis

Reproductive characteristics of Korean pine (Pinus koraiensis S. et Z.) clones were surveyed at two clone banks for 3 consecutive years. These clone banks were established at Yongin, Kyonggi-do and Chunchon, Kangwon-do in 1983. Characteristics in female and male strobili were investigated spatially (between locations) and temporally (among investigated years). Broad sense heritability varied from 0.20 to 0.46 in females and from 0.34 to 0.56 in males. Among 161 clones, 32 clones (20% of the total clones) accounted for 42-54% of clonal contribution in female strobilus production and 83-96% in male strobilus production, suggesting that the clonal contribution for male parents was severely unbalanced compared to that for female parents. The degree of sexual asymmetry varied with a range of 0.07 to 0.44 at Yongin and 0.03 to 0.24 at Chunchon. The effective numbers varied depending on years, locations and genders. The mean values of relative effective numbers at gamete levels were 0.56 in female and 0.09 in male, and that value at the zygote (i.e., clone) level was 0.27 (0.25 at Yongin and 0.29 at Chunchon), respectively. From the results, some management options, such as supplemental mass pollination, flower stimulation and equal seed harvest are suggested in the seed orchard of P. koraiensis.