Studies on the Physiology of Nodule Formation: III. Experiments on the Excision of Root-tips and Nodules

The excision of nodules and root-tips from red clover inoculated with an effective strain of nodule bacteria leads to an increase in the number of nodules subsequently formed. This is thought to be due to the removal by excision of the source of an inhibitor. In the nodule the inhibitory activity appears to be centred in the growing-point and not in the bacterial tissue, since the excision of the nodular meristem only will stimulate further nodulation. The response to excision depends upon the number of excisions made and is inversely related to the inherent susceptibility of the individual plant.

Excision of nodules from plants inoculated with ineffective strains of bacteria has no influence on further nodulation, presumably because the growing-points of the nodules are abortive.
RESP-3053