Objective This study aimed to select high-yielding and superior-quality clones from the clonal seed orchard of Pinus koraiensis established in 1984 in the Weihe region, through an investigation of fruiting traits, determination of seed and nutritional traits, followed by principal component analysis (PCA).
Methods The fruiting traits of clones in the Pinus koraiensis seed orchard were investigated, and seed and nutritional traits of the selected high-yield clones were determined. Statistical analyses including variation analysis, analysis of variance (ANOVA), correlation analysis, and principal component analysis (PCA), were employed for selecting high-yield and superior-quality clones.
Results Variation analysis of fruiting traits across 99 clones revealed a high average coefficient of variation (CV) of 153.4% for the total number of cones per tree, whereas the CV for the number of cones per fertile tree was relatively low at 85.0%. Based on the criteria that the average number of total cones and fertile tree cones exceeded the population mean, 37 high-yield clones were initially selected from the 99 clones. ANOVA of the seed and nutritional traits of these 37 clones revealed extremely significant differences in key traits including cone dry weight, seed weight per cone, number of seeds per cone, 1000-kernel weight, 30-kernel weight, kernel rate, seed rate, triglyceride content, and protein content. Protein content showed the lowest CV at 6.4%, indicating high genetic stability. Correlation analysis indicated that yield-related traits, such as cone dry weight, were extremely significantly positively correlated with seed weight per cone (r=0.866, p<0.01). Nutritional traits, including triglyceride and protein content, showed weak correlations with both morphological and yield indices (|r|<0.24). PCA on the eight seed and nutritional traits of the 37 clones identified the top 20% of clones based on the comprehensive score. Five superior-quality clones (No. 170, 160, 24, 86, 102) were selected. Compared with the population mean, these five clones showed a 5.88% increase in total cone number (average 15.3), a 12.9% increase in cone dry weight (average 197.7 g), an 8.8% increase in 1000-kernel weight (average 649.7 g), a 7.1% increase in kernel rate (average 35.2%), and a 5.4% increase in triglyceride content (average 56.2%). Multiple comparison analysis showed that these clones ranked among the top 15 for 1000-kernel weight, average cone length, number of seeds per cone, and 30-kernel weight.
Conclusion A two-stage selection process was applied: first, 37 high-yield clones were selected based on fruiting traits; second, the top 20% were selected based on comprehensive seed and nutritional trait rankings, eliminating inferior clones. Ultimately, 5 superior clones (No. 170, 160, 24, 86, 102) were identified, demonstrating excellent overall performance characterized by high fecundity and superior nutritional quality. The breeding method proposed in this study provides theoretical guidance for the evaluation and selection of elite Pinus koraiensis varieties, and the selected superior clones can be promoted in mountainous areas of Heilongjiang and regions with similar site conditions.
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