2020 Volume 89 Issue 3 Pages 236-244
Efficient cultivation management of raising seedlings is required in transplanting rice cultivation. However, in Akita prefecture, the techniques for raising seedlings to stabilize production is labor-intensive. We seeded 180 g of seeds (dry weight) in a nursery box, and raised them in a vinyl house without warming (180 g seedlings hereafter). For comparison, we seeded 100 g of seeds, which is the conventional seeding density by the same method (100 g seedlings hereafter). We used two rice varieties ‘Akitakomachi’ and ‘Menkoina’. The characteristics of these seedlings and their growth after transplanting were compared. The leaf number of the 180 g seedlings was over 4, but was 0.3–0.8 less than that of the 100 g seedlings. The number of nursery boxes used for transplanting the 180 g seedlings was 64–77%％of that used for transplanting the 100 g seedlings. After transplanting, tillering from the lower nodes of the 180 g seedlings increased as compared with the 100 g seedlings. In cultivation of the 180 g seedlings, second tillering occurred frequently, the number of tillers in the highest tillering period increased, and number of panicles also increased. The growth stage from the young panicle formation stage to the maturity stage was delayed by 0-3 days as compared with the 100 g seedlings. The leaf color of the 180 g seedlings during the ripening period remained high. The yield of the 180 g seedlings was higher than that of the 100 g seedlings and the quality of brown rice was the same. These results demonstrate the usefulness of the high density (180 g seedlings) labor-saving and stable production method for transplanting rice cultivation.
