Effect of Nitrogen Management on Rice Growth and Yield under Different Seedling Density in Puddled -soil Drill Seeding

This study was carried out to clarify the proper nitrogen application methods under the different seedling density in puddled-soil drill seeding of rice. Seedling density was adjusted as 30, 60, 90, 120 and 150ea/ just after emergence and nitrogen was applied with five methods including conventional respectively. The maximum tillering stage was shorten as the seedling density was increase but decreased the percentage of productive tillers. Lodging was occurred serverely as the seedling was more than 120ea/, when nitrogen was applied at panicle initiation stage. Grain yield wasn't significantly different among seedling densities when it was more than 60ea/, but the density of 30ea/ was decreased. It wasn't significantly different among the nitrogen application methods when it was more than 90ea/m, but was higher at early application of tillering fertilizer (T) than conventional method when the seedling density was less than 60ea/. Supposing that the yield of reseeding is the same as optimum seedling density, minimum seedling density needs for reseeding would be less than 55 ea/ as the aspect of income allowed for managing expense.