Relationships between the Growth Direction of Primary Roots and their Anatomical Characters in Rice Plants

Abstract

Relationships between the growth direction of primary roots and their anatomical characters in cross sections were examined in rice plants. A close relationship was found between the root diameter and the stele diameter (r=0.966). And also there was a high correlation between the stele diameter and the phloem pole number (r=0.767). From the detail examination, however, it is shown that the latter regression line was variable depending on the growth direction of roots respectively. Then, as an index of the ratio of the stele diameter to the phloem pole number, the interphloem distance (=stele diameter×3.14/phloem pole number) was examined, and a relatively high correlation was found between the growth direction of the primary roots and their interphloem distance (r=0.702). From the observations described above it is suggested that the interphloem distance is, at least in this case, one important key to solve the problems of the root growth direction.