Background : Seed germination for Adenophora triphylla var. japonica Hara. is not good when grown in direct seeding. This experiment was conducted to identify seedling box suitable for seedling transplantation and cultivation to improve farm income and public health.
Methods and Result : To investigate the effect on growth, sizes of seedling box used were as follows (width × length × height, in ㎝); 2.5 × 2.5 × 4 (custom), 4 × 4 × 4, 4.5 × 4.5 × 6, 5.0 × 5 × 9.6, 5 × 5 × 11.2, 5 × 5 × 17, and for sowing in narrow strips; 33.5 × 55 × 13, 33.5 × 49 × 23, 33.5 × 49 × 30. The weight of the ground part decreased as box height became lower, highest at 17 ㎝ tall (0.65 g) and lowest at 4 ㎝ (0.23 g). In terms of root length of the seedlings, the longest was 9.0 - 9.3 ㎝ at box height of 17 ㎝ and decreased as height decreased. Root weight increased as box height decreased, the highest at 4 ㎝. After the seedlings were planted, more than 90% survived in seedling box compared to the 50% rooting rate on sown in narrow strips where root net formation did not occur. During harvesting period, plant height was 15.8 - 17.5 ㎝ with a shoot diameter of 13.3 - 20.7 ㎜, leaf length of 5.6 - 7.9 ㎝ and leaf numbers 15.6 - 22.3. Moreover, leaf width was the widest at 8.6 ㎝ at 6 ㎝ box height while dry weight was the most at 6.7 g at 11.2 ㎝. Survival rate and growth characteristics of the ground part were lower in seedling box for sowing in narrow strips. For the underground characteristics, root number increased as box height decreased while dry weight increased as box height increased, with 1.7 - 3.5 and 6.2 - 6.8 less in seedling box for sowing in narrow strips, respectively. The yield in a 17 ㎝ high seedling box was 152 ㎏ per 10 a, 16% higher than conventional level, and decreased as box height decreased.
Conclusion : These results suggest that the optimum seedling box height is 11.2 - 17 ㎝ to have lower root numbers and higher dry weight and yield.