Studies on the Development of Various Parts of Paddy Rice Plant : I. Elongation and changes in dry weight of the parts and organs of rice plant and interrelation among them, during the elongation period.

The process of the elongation and the change of dry weight of certain parts or organs, such as leaf-blades, leaf-sheaths, internodes and panicles were studied. The increase curves of the length and the dry weight of organs showed S shapes (Fig. 1 and 2). The dates of the maximum velosity of the elongation of organs occured nearly at the same time among (B0:S1:N2), (B1:S2:N3), and (B2:S3:N4) respectively, where B1:B2:···, S1:S2:···, N0:N1:··· indicate the order of blades, sheaths and internodes from the uppermost ones downwards, the panicle being indicated as B0. The interrelation among the different organs with respect to the change in dry weight was roughly alike to that with respect to the elongation process; but the duration of the dry matter accumulation in each organ was fairly long, so the amount of dry matter required was balanced. When the velosity of the elongation of organs was maximum, the increase in dry weight became large; and when the increment of dry weight was maximum, the elongation was about to finishi During the booting stage, when the increase in weight of the panicle was large, the increase in weight of the other organs was retarded. After the heading time, during the period where the increase in weight of the panicie was large, the weight of sheaths rind internodes decreased; but, later, when the increasing trend in panicle weight declined, the decrease in weight of sheaths and internodes stopped, and they began to restore. Blades scarcely showed such signs of rise or fall. The increase in the total weight of a stem was related to the mumber of hours of daily sunshine.