Full-sib progeny test and early selection in superior families of Betula platyphylla

Carrying out afforestation test of full-sib families can not only select excellent hybrid parents and combination, but also accelerate the improved process of seed orchard. In this study, 20 progeny seedlings were got from seed mother trees in seed orchard by tester strain mating design.Tree height (H), diameter at breast height (DBH) and volume (V) of tested trees, which were planted 6 years ago in Maoershan Mountain of northeastern China, were measured and analyzed. The results showed that there had highly significant differences (P < 0.01) in H, DBH, and V among different female parents and varied hybrid combinations, and there had significant differences (P < 0.05) in DBH and V among different male parents. According to the results of multiple comparisons, excellent male and female parents were selected. Meanwhile, the tested hybrid combinations were synthetically evaluated by multi-objective decision-making method. The top five combinations were defined as superior hybrid combinations with the comprehensive evaluating value greater than 0.80, and the selection ratio was 25.00%, among them Q2 and Q19 family were the best hybrid combinations. The average of selected excellent hybrid traits were 3.85%, 10.01%, 20.82% higher than that of overall, the genetic gain was 2.90%, 7.64%, 16.22%, respectively. These results provide a theoretical basis for selection of birch full-sib progeny and a reference for affinity option of birch high generation seed orchard.