Clonal variations in cone, seed and nut traits in a Pinus koraiensis seed orchard in Northeast China

Korean pine (Pinus koraiensis Siebold & Zucc.) in Northeastern China has been genetically improved to increase seed yields in addition to timber. To assess seed yield variability and select highly productive clones, 14 cone, seed and nut traits were measured and analyzed. Variance analysis showed that all clones were significantly different in various traits (P < 0.01). Phenotypic coefficients of variation and repeatability of traits ranged from 9.1 to 34.4% and from 27.5 to 97.7%, respectively. Except for the cone layer and cone seed numbers, the other traits were positively or negatively correlated. Three principal components were identified. Seed and nut traits were the most important traits in the first principal component, and cone traits more important in the second. Using correlation and principal component analyses, cone number and other traits were selected to evaluate materials. Twenty-two clones were selected using a selection rate of 10% based on cone number independently or other combined traits. The genetic gain for different traits ranged from 6.2 to 24.3%. The selected elite clones can supply seedlings for reforestation and the selection method can provide a theoretical basis for selection in other conifer species.