Abstract
It became clear that the successive elongation in seminal root and the development of laterals depended upon the nitrogen and phosphorous derived from the cortical disintegration in aged root parts, after supply of the same from endosperm to seminal root had ceased. This result indicates that the seminal root axis on and after 4th day was composed of two parts, the one formed by utilization of nitrogen and phosphorous from endosperm and the other from aged root regions. Two types of lateral roots in growth pattern emerged from these parts respectively. The first type emerging from the former regions had an increasing protein synthetic pattern during the growth. On the other hand, the second type gave a pattern increasing cell wall substance synthesis during the growth. While the synthetic character in nitrogen and phosphorous metabolism was converted into catabolic one on each parts in root axis, begining with the rooting of laterals, the increase of lacunae formation synchronized with them. In these parts about 50 to 60 % of the nitrogen and phosphorous contained in root cylinder was translocated to younger root parts during cortical disintegration. For this reason, the cortex of rice root seems to be regarded as the reserve tissue of nitrogen and phosphorous compounds.
