On the Development of Branch-roots on successive Nodes in Rice Plants (II)

[摘要] As previously mentioned (1959), branching of root, ie, formation of primary, secondary, tertiary rootlets and so on, proceedes at the same pace as the leaf emergence at a successive node in rice, wheat and corn plant. In this experiment, the auther has planned to observe morphologically the mechanism of root branching and to make clear the growth of roots in paddy rice. The results obtained were: 1. In a transverse section of the roots in rice, wheat and corn it was observed that, the branch-roots originate from the cell of the pericycle opposite the phloem of the vascular bundle of its root, but not from the points opposite the xylem. Conseguently, the formation of the branch-roots is correlated with the number of the phloem. Therefore, with late maturing varieties the number of the branch-roots, is greater than with earlier maturing varieties because the late maturing varieties have many phloems than those of the earlier ones. 2. Observing morphologically the root branching, it was found that branching has a close relationship with the curvature of the root. The branch-roots are produced usually at the convex portion of the curvature, but not at the concave portion. Moreover the greater is the curvature the greater and bigger the branch-roots. And also when the roots were curved artificially, the same tendency was recognized as in the natural condition. 3. When we compare the curvatures of the roots growing in paddy field condition with these in up-land condition, the former was more gentle than the latter and big branch-roots were few in paddy field condition than in up-land.

[学科分类] 农业科学（综合）