Abstract
This research was conducted to establish the method of direct seeding of iron-coated seeds using air-assist row seeder in the cold district. The defensive effect of iron-coated seeds direct-seeded in a submerged paddy field against birds was examined. In addition, seedling emergence and establishment of seedling from directly seeded iron-coated seeds, pre-germinated seeds, and calcium peroxide-coated seeds were comparatively examined in pot experiments. Iron coating was more effective in defending the seeds from bird damage than coating with calcium-peroxide due to the reduced lightness (L*) and increased red (a*) and yellow (b*) hues caused by oxidation of iron. In short, the iron-coated seeds were not easily damaged by bird because the appearance was similar to that of the soil surface. On the other hand, the iron-coated seeds showed delayed seedling emergence and establishment compared with the calcium peroxide-coated seeds at low temperatures and under conditions of deep seeding. We propose that seeding of iron-coated seeds on the soil surface is preferable for direct seeding in submerged paddy fields. The introduction of new methods that promote seedling emergence and establishment may be advantageous in cold areas.
