2026 Volume 108 Issue 6 Pages 137-144
In recent years, the production of container-grown seedlings has expanded in Japanese forestry to ensure a stable supply of planting stock; however, difficulties in adjusting nursery density and the labor required for container management remain major challenges. This study aimed to evaluate the practical applicability of biodegradable paper pots by comparing the growth characteristics and seedling traits of Cryptomeria japonica seedlings grown in paper pots with those grown in M-Star containers, which also allow flexible density adjustment and are increasingly used in practice. Two growing trials were conducted in 2024 and 2025, in which seedling height, root collar diameter, above- and belowground dry mass, and shoot-to-root ratio were measured. In addition, soil moisture content and soil temperature within the containers were monitored, and initial survival rates were compared through planting trials at two sites. As a result, no pronounced differences were detected between container types in these growth and traits, while interannual variation had a relatively greater influence. In contrast, soil temperature in paper pots tended to be lower during daytime in summer. Post-planting survival rates were higher than 88% at two planting sites, with no significant differences between pot types. These findings suggest that paper pots are highly practical and capable of producing seedlings comparable to those grown in M-Star containers under identical nursery conditions.
