Objective  To evaluate the quality of one-year-old container seedlings of Dalbergia cochinchinensis, and provide a technical basis for its seedling cultivation and plantation development.

Method  Seedling grading indexes were determined by principal components analysis. We used the mean ± standard deviation and progressive clustering methods to analyze the proportions of seedlings in different grades, grading standards and differences among grades in afforestation effects at early stage of seedlings in Yangjiang, Gaoming of Guangdong and Zhangzhou of Fujian. The suitable grading method and standards were determined.

Result  The principal component contribution rates of seedling height (H) and ground diameter (D) were 59.85% and 26.02%, respectively. H and D could be used as the grading indexes for one-year-old D. cochinchinensis seedlings, and these traits were significantly different among different graded seedlings. The cumulative variance contribution rate of seedling height and ground diameter was 85.87%. There were no obvious differences in the proportions of seedlings in each grade and grading ranges between two grading methods. Qualified D. cochinchinensis seedlings (Grade Ⅰ and Ⅱ) determined by the mean ± standard deviation method performed well in the early growth period and had higher survival rates (>90%) at all test sites. Seedling traits and survival rates after planting of 3 and 12 months had highly significant positive correlations withH and D at planting time.

Conclusion  The mean ± standard deviation method is more feasible for grading of one-year-old D. cochinchinensis seedlings by comprehensively evaluating the proportions of seedlings in different grades, ranges of grading indexes, early afforestation effect and practical seedling cultivation. The grading standards are as follows: Grade Ⅰof H ≥ 119.76 cm and D ≥ 7.66 mm; grade Ⅱ of 69.62 cm ≤ H ＜ 119.76 cm and 5.04 mm ≤ D ＜ 7.66 mm; grade Ⅲ of H ＜ 69.62 cm and D ＜ 5.04 mm.