Studies on the Physiological Function of the Crop Roots. : (II) Nitrogen metabolism and growth responses in the rice plant in which RNA synthesis of the roots was inhibited by soaking the roots in ribonuclease solution.

Abstract

In the case of root injuried, it was observed that protein breakdown occurred with rapid decrease of RNA in the shoots of rice plant (from the previous report). Accordingly, author considers that RNA metabolism of the roots played an inportant role im nitrogen metabolism of the shoots. In this experiment, RNA synthesis in the root was inhibited by soaking the root in ribonuclease solution. Results obtained are as follow: (1) The content of protein-nitrogen decreased with the increase of soluble-nitrogen and this tendency attained maximum at the concentration of 500 ppm RNase. (2) The ratio of protein-N/soluble-N fell with the lapse of time, and soluble-nitrogen attained maximum at the 8th day after treatments and then decreased. (3) The rate of growth in the term of fresh weight was greatly retarded by RNase-treatment during the 8 days. After that, this tendency was disappeared and the growth of the shoot recovered. (4) As regards the relationship between roots and shoots, it was observed that elongation of the newly developing leaf was largely affected by the treatments of rots, and with the cessation of the treatments, new roots developed so quickly that new leaf began to appear. This fact suggests that there is close relationship between development of new roots and formation of new leaves.