抄録
This experiment was undertaken with the purpose of clarifying the expansinn of tillering attitude and the lodging resistance of rice plant caused by 2, 4-D treatment. The results obtained may be summarized as follows. Rice plant treated by 2, 4-D expressed the expansion of tillering posture under daylight, but did not show it under interception of light. 2, 4-D caused an increased content of glucoce and starch in culm, leaf sheath, and spikelets, especially in culm base indicating a promoted distribution of glucose and starch to culm with a consequent decrease in the distribution to spikelets as observed at 30 days after heading. The dry weight of culm base and breaking strength of it are also increased by 2, 4-D. These changes of culm base property were more remarkable when 2, 4-D was applied under the condition in which culm base was intercepted to light and was closedby a hemp cord not to make culm base open, but the degree of changes of culm property, caused by the artificial expansion of tillerng attitude, was less than 2, 4-D treatment except the increase of breaking strength in culm, base. From these results, we concluded that the effect of 2, 4-D in increasing culm strength and lodging resistance is not primarily due to the expansion of plant attitude but to the specific function of 2, 4-D.
