A labor-saving, nursing seedling system for male-sterile Japanese cedar using  agricultural machinery.

Abstract

This study used an“onion seedling transplanter”to reduce the labor associated with transplanting Japanese cedar seedlings. This method allowed approximately 1800 seedlings to be transplanted per hour per worker compared with approximately 150–180 seedlings per hour per worker using the hand planting method. This indicated that use of the machinery enhanced the work efficiency by > 10 times. The appropriate cell size of seedlings for the machine was approximately 5–15 cm. We found that the largest proportion of seedlings met this standard when they were sown in the middle of May. The seedlings were then sorted in the middle of August, and seedlings that were > 10 cm in height were sprayed with the growth suppressor Ethrel 10, whereas those with < 5 cm in height were given additional fertilizer treatment to promote their growth. This treatment resulted in approximately 90% of the seedlings meeting the standard of the machinery. Second-year Japanese cedar seedlings are generally transplanted in spring. However, to distribute the nursery-related work throughout the year, we transplanted the seedlings in the fall of the previous year, which resulted in a survival (rooting) rate of approximately 95%. Therefore, shifting the transplanting to fall allowed the annual labor to be more evenly distributed.