On the Cell Wall Thickening of the Endodermis in the Crown Roots of Rice Plants

[摘要] Different roots grown under different conditions of cultivations have shown conspicuous morphological difference in the thickness of the inner tangential and radial walls of the endodermal cells. The degree of the thickness was greater in those roots grown in upland condition than those grown in the submerged one. The thickness of the cell walls of the endodermal cells shows sensitive reaction to the change of the soil conditions during the growing period. In a word, the thickness of the cell walls of the endodermal layer can be induced greatly to a state of typical "U" or "C" shape in appearance of transversal views. This phenomena are closely correlated to the soil water conditions. Further observations of the endodermal cells reveal the following morphological features; first, the existence of cytoplasm and nuclei in any stage of the development and second, numerous small pits in the thickened inner tangential, radial and transversal walls. The degree of thickness, in usual, is correlated to the orientation of the tissue elements of the stele and sometimes the passage cells were found opposite to the protoxylem elments. The differences in thickness of the endodermal layer in the roots which keep close correlation to the soil water condition, together with sorne typical characteristics shown in the cells of this layer may have endowed quite specialized function in regard to the physiological mode of water utilization by the roots of rice plants grown in paddy fields.

[学科分类] 农业科学（综合）