Flowering variation and its effect on the gene diversity of seed crops in a clonal seed orchard of Pinus koraiensis Siebold et Zucc.

Pinus koraiensis, an economically and ecologically vital five-needle pine species, was surveyed for female and male strobilus production variation among 52 clones over five years in a seed orchard in Gangwon province of South Korea. We estimated heritability, effective population size and gene diversity, calculated maleness index, and drew parental balance curves for the strobilus production annually. Results demonstrated marked variation in female and male strobilus production among clones and years, particularly in male strobilus production. The maleness indices indicated a considerable deviation from sexual balance. Parental balance curves revealed that the top 20% of the most fertile clones contributed significantly to the total strobilus production. High heritability values underscored the substantial genetic influence on strobilus production. The gene diversity of orchard parents (GDp) was set as one (GDp = 1) considering panmictic situations, and then loss of gene diversity in the female gametes (GDf) was relatively estimated to be ranged from 0.096 (loss = 1 − GDf = 1 − 0.904, 9.6% in 2017) to 0.017 (= 1 − 0.983, 1.7% in 2020). We emphasize the importance of the effective number of parents as a crucial parameter for informing seed orchard management decisions. [ABSTRACT FROM AUTHOR]