Abstract
The authors found out from the results of previous experiments that some morphologicali changes of corn plants by the wilting treatments were due to the raising of auxin level in the neighbouring of nodes, but it has been unknown what is a main cause in its process, namely, whether the raising of tryptophan (TTP) as the precursor of IAA produced of common proteins by hydrolysis or the conversion of bound auxin to free auxin. In order to discuss these problems, the spray treatments on corn plants with tryptophan (TTP) and naphthalene acetic acid (NAA) solutions were tried. 1. Both NAA-spray treatment and TTP-spray treatment on corn plants accelerated the internodal elongation, and the differential influences have beep observed remarkably in the case of the former treatment in comparison with the latter. The former made the interrnodal elongation accelerate considerably on each internode which had finished their elongation or was elongating vigorously. On the internodes which were going to elongate, the latter made those elongation accelerate, but the former made them reduce even with lO ppm solution. 2. The slack influence appeared on the elongation of leafblades under TTP-spray treatment, because each of leaves appeared after the treatment was made to increase in length. NAA-spray treatment have influence on the elongation of all leafblades which were elongating and it accelerated those elongation directly with lOppm solution, but reduced with lOppm solution. 3. The influence of TTP-spray treatment on the growth of born plants was confirnled repeatedly and the results were like the wilting treatment that brought on the increace of the length of internodes and leafblades. 4. It seems that the increase of auxin content in the neighbouring of nodes under the wilting condition is due to the raising of TTP produced of common proteins by hydrolysis.
