Abstract
Effects of puddling in submerged direct rice seeding on seedling emergence and establishment after draining flooded water were investigated in pot experiments to establish the seeding method with a newly developed "Shooting hill-seeder". Draining flooded water after seeding rice seeds coated with calcium peroxide into puddled soil changed the three-phase ratio of soil and soil structure in the surface soil proportionally to the degree of puddling before seeding. In addition, water-holding capacity (air permeability) of soil in over-puddled pots was higher (lower) than that in normally puddled ones. Seedling establishment rates of rice seedlings at two weeks after seeding in over-puddled pots were lower than those in normally puddled pots, especially when seeded deep and wheat straw was applied. Furthermore, dry weights of shoots and roots of seedlings were affected by the degree of puddling. These results suggest that normal puddling (not over-puddling) improves both seedling emergence and establishment after draining flooded water following seeding of rice, especially when seeded deep and wheat straw was applied.
