Abstract
By means of the "leaf-cutting" method and under different light conditions, the relationship between the growth of crown roots and their branching habit was investigated in rice plants. Under shaded condition, as compared with the control, both diameter and growth rate of crown roots decreased remarkably, while the decreasing rate per day of their diameter remained almost constant. Irrespective of the differences in light conditions, a close correlation was found between the branching habit and the growth characteristics of crown roots. Namely, the density of laterals was higher on the crown roots, in which the diameter as well as growth rate decreased more rapidly, as exemplified in crown roots grown under shaded condition. In such crown roots, however, the total number of laterals formed within a definite time interval tended to be less, due mainly to the limited growth rate of the crown roots.
