The present paper deals with the influence of the intensity and its persistence of nitrogen supply to the formation and development of the organs of rice plant and als with the resulting physiological feature of these influences. Pot culture experiments with paddy soils were conducted in open field. Organic manure and ammonium sulphate were applied at different stages of growth, i.e. tillering, internode elongating and panicle differentiating stage. The results are summarized as follows: 1. Experiments revealed that various organs of rice plant gave different responses to the status of nitrogen supply, and to the same organs, their responses of nitrogen varies at different stages of growth. At the tillering stage, a strongly intensified and less persistent supply of nitrogen, as in the case of ammonium sulphate, promoted the assimilation of dry matter in leaf blade, and consequently enlarged the leaf areas. Such effect on the leaf blade, however, terminated after the internode elongating stage, and more accumulation of dry matter was found in the stems. Top dressing of manures, pertinently after the internode elongating stage, gave a moderate but persistent supply of nitrogen at that time and resulted the formation of large and healthy ears. Under the experimental condition, such treatments have been proved favourable to the growth and yield of rice.