Initial growth and root system development of Cryptomeria japonica cuttings using different nursery methods

Using Japanese cedar ( Cryptomeria japonica ) cuttings developed through different methods, the effect of various initial underground root shapes on subsequent growth was evaluated by understanding various above- and belowground traits at the initial planting stage. The cuttings developed through four different techniques were used in this study: bare-root cuttings grown in an open field, BCC-containerized cuttings, biodegradable-containerized cuttings, and JFA150-containerized cuttings grown in greenhouses. After planting in December 2019, different parameters, namely, survival rate, seedling height, and ground diameter, were measured over three subsequent growth seasons. In addition, resistance to vertical pulling and digging out was determined to assess the development of the root system from each cutting. No statistically significant differences were observed in the survival rate and ground diameter of various cuttings after three growth seasons. Meanwhile, a statistically significant difference was noticed in the seedling length of the bare-root and containerized cuttings during the first growth season. After two growth seasons, the T/R ratio—a measure of root system development—reached a value of 4—a typical or benchmark value for healthy Japanese cedar growth—in all the cedar cuttings. Under dry conditions, the presence of a root ball reduced stress at the initial planting stage in all the containerized cuttings, making containerized cuttings an effective propagation method for Japanese cedar. The maximum resistance value in the root pull-out test showed a strong correlation with the root volume.