Studies on nitrogen metabolism of the rice plant in relationship to its growth

Introduction Absorption of nitrogen by the rice plant in relationship to its growth, and its movement within the plant as a whole have recently been made quite clear1),2. The recent advance in the analysis of the processes of rice plant growth, clarified that feature of nitrogen movement is quite different according to the portion of the rice plant. Togari3 and this writer4 reported that leaf blade is invariably higher in nitrogen concentration and quantity than leaf sheath or culm, and nitrogen moving to the ear at maturing stage is mainly derived from the leaf blade. Tanaka5 went still further, making it clear that individual leaves are different in their mode of nitrogen metabolism, which can be divided into three groups according to their position on the stem.