0023-6152

AA00697606

22807

Unrefereed

0023-6152

AA00697606

The existence of gibberellin-like substances in ethanol extracts of the seedlings, the upper leaves at the internode elongating stage and the etiolated seedlings grown in darkness of dwarf and normal varieties of rice plants were examined by paper chromatography with ammonical iso-propanol. The effects of the darkness and GA, on the internode elongation of these plants were also investigated. In the seedling stage, the gibberellin-like substance (Rf 0.4-0.7) was found in both dwarf and normal rice plants and this substance corresponded to GA,. However, its amounts differed from each other. Specifically, Daikoku contained more this growth promoting substance than Kotake-tamanishiki. In all the dwarf varieties used in the present experiment and in the normal variety “Kinmaze”, an inhibiting substance was found in the region of Rf value 0.8-1.0. This substance was especially pronounced in “Daikoku”. On the other hand, another growth promoting substance appeared in the region of Rf value 0.0-0.3. Extracts of the upper leaves in the internode elongating stage contained two growth promoting substances in both dwarf and normal rice varieties (Rf 0.0-0.3 and 0.4-0.7). It was found that there was no difference between dwarf and normal rice plants in the amounts of GA3, but the other gibberellin-like substance (Rf 0.0-0.3) was more abundant in normal than in dwarf rice plants. In the dark condition, the dwarf type, ” Tankan-shirasasa ‘0 shows a great elongation of the internode that is nearly equal to the normal type, but in this dwarf type the elongation of the internode is not promoted by the GA, treatment. The amount of gibberellin-like substance (Rf 0.4-0.7) in the dwarf types grown in the dark was not different from that of the normal ones. These results may suggest that the dwarf gene of the dwarf rice variety “Tankan-shirasasa” is closely connected with the elongation of the lower internode, and that the elongation of it was promoted by a gibbercllin-like substance (Rf O&0.3), although in this variety this substance was disturbed by light illumination.