抄録
The stimulating effects of gibberellin and auxin on the elongation of a lamina joint in rice have already been indicated, based on a phenomenon increasing the lamina inclination in Bakanae diseased rice plants. In this communication, the effects of divalent cations, especially calcium ion, upon the elongation of the lamina joint are detailed, using the second leaves excised from etiolated rice seedlings. It has been proved that the various divalent cations at even 0.002 N excrise a depressive effect on the IAA induced elongation (Table 1), and that furthermore the calcium ion decreases the elongation induced by NAA alone or NAA-gibberellin interaction (Fig. 2). At 0.0005 N to 0.01 N potassium ion strengthens the elongating effect of various concentrations of IAA (Tables 2 and 3). And more, the potassium ion recovers the inhibitive action of the calcium in the elongation (Fig. 3). From the above mentioned results, we compared among the interactions of gibberellin and IAA, of gibberellin and potassium, and of IAA and of potassium, upon each other. The interaction between gibberellin and IAA was much larger than the others. Above all, the reversed effect of the potassium ion on the Ca induced inhibition under the interaction of gibberellin and IAA has been revealed in this paper (Table 4). Thus, it was presented that gibberellin has an accelerating action in the interactions of gibberellin and auxin or potassium ion on the lamina inclination which bring about an elongation in the lamina joints of rice plants. From these facts we may show one facet of mechanisms of gibberellin action, in relation to those of auxin action.
