Physiological studies on the poisonous action of 2.4-D on plants. : I. On the synergisme of 2.4-D and potassium chlorate for killing weeds.

Abstract

In the present experiments, we studied the poisonous actions of 2.4-D on Jerusalem Artichoke and the synergisme by means of the mixed application and the continued spread of 2.4-D and KC1O₃. The single application of 2.4-D as a spray to the foliage of the growing plant induces the following physiological changes within it. (1) The transpiration activity is accelerated soon after the application of the herbicide. (2) The assimilation intensity is reduced. (3) The cell-sap concentration, however, tends lower. (4) The vitamine C contents are much reduced. (5) The resistance to the toxic action of KClO₃ of the foliage sprayed with 2.4-D a few days before gets obviously stronger. This is ascribed to, according to Yamasaki's hypothesis on the harmful effect of KClO₃ upon the plants, that the sprayed foliage with 2.4-D is poor in reducing matters which reduce KClO₃ to KClO, the harmful substance to the plant. The mixed application as a spray of two kinds of herbicides noted above resulted in much quick killing of the plants when compared with the single application of each chemical, thus the "synergisme" being clearly demonstrated. This is partly due to, it is supposed, that 2.4-D injures the upper parts of the sprayed plants, whereas KClO₃ kills the lower parts.