Variation in cone and seed traits in a clonal seed orchard of red pine (Pinus koraiensis Sieb. et Zucc.)

Previous studies on cone/seed traits of conifer seed orchards have focused on genetic variation, while non-genetic variation has rarely been investigated. This study examined the variation of cone/seed traits in a red pine clonal seed orchard in 2008 and 2018. The registered cone traits included size, weight, the number of seeds(-cone), number of scales(-cone) and number of cones(-tree) and seed traits included size, weight, kernel weight and shell thickness. For cone traits other than cone size in 2018, which were under strong genetic control, the variation was largely and similarly contributed by interramet and intercone variations. For seed traits, over 90% of the variation was due to non-genetic factors, with contributions from interseed intertree > intercone. While heritability estimates for cone size were high, those for other cone traits and all seed traits were low on broad-sense basis (0.10) but moderate on clonal mean basis (0.35). Genetic correlations between cone or seed traits were positively moderate to strong other than the number of cones(-tree), which correlated negatively with all other cone traits. The genetic correlations between cone and seed traits were weak, paired with mixed signs. The implications of these findings to manage seed orchards or advanced breeding were discussed.