Abstract
We examined the effects of the amount of iron coating, seeding depth and water management after seeding on seedling emergence and establishment of rice direct-seeded in a submerged paddy field in Hokuriku region. The results of a field survey showed that air temperature and water management after seeding influenced seedling establishment. However, the influence of the amount of iron coating was not distinct. In the field experiment, the seeds coated with iron powder, a quarter and half times as heavy as seed dry weight (Fe 0.25 and Fe 0.5), and with calcium peroxide were sown under different water management (drainage, wetness and flooding) conditions. The rate of seedling establishment was higher in Fe 0.25 than in Fe 0.5 and in the drained and wet plots than in the flooded plot. Furthermore, the rate of seedling establishment was decreased by seeding below the surface of soil more greatly in the iron-coated seeds than in the calcium peroxide coated-seed. In the vat experiment, seedling emergence of the seed sown on the soil surface was delayed by drainage, but seedling emergence was increased with increasing seed moisture. In the seed seeded below the soil surface, seedling establishment was decreased by flooding. To improve the seedling establishment of direct-seeded iron-coated rice, it is important to sow Fe 0.25 seed on the soil surface and drain after seeding, and to supply the moisture necessary for germination to the seed.
