Investigations on several basic problems such as growing media, transplanting time, application of slow release fertilizers and overwintering for the container grown ornamental trees were carried out to enable year-round planting and to increase survival rats after planting.
1. Results about the media used for container grown trees:
a) Korean black peat used en its own was the best for the growth increment of Prurus yedoensis and Acer palmatum. This medium kept the highest level in moisture recreation and total nitrogen. In Prurus karaiensis, fertile soil mixed with decayed rice-straw or humid sawdust showed better growth than other container media.
b) A medium consisted of six parts of briquet ashes mixed with four parts of fertile soil by volume resulted in good growth Prunus yedoensis whereas a medium containing three parts of briguet ashes mixed with seven parts of fertile soil by volume showed good growth in Pinus karaiensis. For both of the container grown plants, the medium used the Korean black peat only gave better growth than the media mixed with the briquet ached and the fertile soil. This growth tendency positively linked with the level of total nitrogen and moisture retention.
c) Basic medium added with materials increasing the ration exchange capacity (C.E.C.) always showed better growth than the media without them. The growth of container grown plants was better than the field grown ones. Among the treatments with interials increasing the C. E. C., zeolite 30㎏, black peat 15㎏, black peat 30㎏ and vermiculite 30㎏ in basic medium of 1㎥ respectively, for Abies holophylla all the treatments except for vermiculite were sultable and for Gingko biloba black peak 15㎏ and vermiculite 30㎏ were suitable. The growth of investigated trees generally paralleled with the level of total nitrogen and C. E. C.
2. Growth differences were not statistically significant between sulphur coating urea (S.C.U.), a fertilizer releasing slowly applied once or twice a year and urea applied weekly or every two weeks. Total nitrogen level of the medium fertilized with S.C.U. was slightly higher than urea applied one.
3. Despite the three times of off-season transplanting, survial ratio of container grown plants wire 100% except for Pinus parvifiora which survived 80%. The container grown plants . gave mole vigorous growth than the field grown ones.
4. In 1976 having a severely cold winter, for Prunus yedoensis, Acer palmatum and Pinus koraiensis burying the container at the ground level gave 100% survival whereas keeping them without protection resulted in 100% death. While mounting the container with soil only gave 100% survival of Prunus yedoensis and Acer palmatum buy 90% survival of Pinus porvifiora.
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