Localization of the photoperiodic perception in potatoes

Summary

It was found that probably all the leaves of young potato plants played a part in perceiving the photoperiodic stimulus which induces tuberization. The importance of the mature leaves in the photoperiodic perception is emphasized by the large tuber yield which could be obtained by subjecting these leaves to inductive photoperiods while the growing tip and young leaves were subjected to non-inductive photoperiods. Tubers were produced under non-inductive photoperiods when the young leaves and meristematic stem apices were removed. Tuberization in these plants could be inhibited by application of gibberellic acid. The developing leaves, therefore, seem to produce a substance, probably gibberellin, which prevents tuberization under long-day conditions. If a specific tuberforming substance is involved it is present in active concentrations even under non-inductive photoperiods. The results are in agreement with the theory that a balance between endogenous gibberellins and another substance(s) controls tuberization.