抄録
In most crown roots of rice plants, usually, the number of secondary lateral roots (per cm of the crown roots) gradually increases from the base towards the tips, comes up to the maximum, and then decreases with decreasing of the diameter of the crown roots. Many other types of branching, are found, i. e., (1) thin crown roots possess abundant secondary lateral roots especially at the apical part. These roots initiate from the upper units of stem and concentrate near the soil surface4) ; (2) some crown roots are conspicuously thick in diameter at the base, though branching features are the same as the ordinary ones mentioned above; (3) roots possess numerous secondary lateral roots in their basal parts. These roots appear just after transplanting in a paddy field ; (4) a group of aberrant roots, which is characterized by short shape, covered with few lateral roots (Fig. 3. 6-9); (5) roots often showing a shape similar to "lion-tail", covered very densely with many thick secondary lateral roots6) (Fig. 3. 12-14); (6) occasionally, faciated secondary lateral roots are found at the base of the crown roots (Fig. 3. 15-19). These roots possess many thick secondary lateral roots and weak ones which can not emerge outside the epidermis of the crown roots; and (7) another type of roots seemed to have grown in upland field, is found (Fig. 3. 20-21).
