Seedling Emergence and Establishment under Drained Conditions in Rice Direct-Sown into Puddled and Leveled Soil —Effect of calcium peroxide seed coating and sowing depth—

Inconsistent seedling establishment is a major constraint in rice direct-sown into puddled and leveled soil. We clarified the effect of water management on seedling emergence and establishment at different sowing depth for seeds with or without calcium peroxide coating. Drainage during 10 to 15 days after sowing scarcely affected the early -stage emergence compared with the wet and flooded conditions. Drainage and wetness promoted the late-stage emergence compared with the flooded conditions regardless of sowing depth and seed coating. The numbers of floating and turned down seedlings, and seedlings with delayed emergence were lower in the drained and wet plots than in the flooded plot. Thus, seedling establishment in such plots was markedly higher than that in the flooded plot, especially when seeds were sown at the soil surface. The dry weight of plants at seedling establishment was greater in the drained and wet plots than in the flooded plot, when seeds coated with calcium peroxide were sown below the soil surface. Drainage during seedling establishment thus improved seedling emergence and establishment regardless of sowing depth and seed coating treatment, and the drainage treatment enhanced the growth and dry weight increase of plants during seedling establishment compared to flooding treatment