Portamento Rampicante - Volubile Provocato, in Alcune Piante, dal Trattamento Con Acido Gibberellico

Summary

In this communication reports are given on experiments and observations regarding treatment of several plants with Gibberellic acid and consequent manifestations of stem growth with twining-climbing behaviour. This phenomenon has been observed in plants which normally never present similar behaviour (Lactuca Scariola L.) and it has been provoked in plants genetically more or less predisposed (Phaseolus vulgaris L. cult. “aquila rossa” e Soja hispida Moench. cult. “Castelli” and “Giessner”). Normally climbing plants, as Ipomaea versicolor, has been treated for control.

In Phaseolus and in Soja the action of Gibberellic acid has been very considerable as plants thus treated have assumed all the characteristics of climbing growth. Photos and Tables clearly show the extent of such action.

In Ipomaea, in conformity with work hypothesis, we can clearly observe the meagre advantage in growth of internodes following tratment with Gibberellic Acid.

The purpose of these experiments, as is obvious, is to lay the bases for a physiological interpretation of climbing behaviour. It is clear by results obtained that, subordinately, at least, to certain qualitative structural manifestations, plants thrive with or without climbing behaviour according to whether their growth is more or less rapid and of different proportions. Increasing growth rapidity by tratment with Gibberellic Acid, we may obtain an twining growth phenomenon in plants genetically more or less predisposed towards said phenomenon, in those plants, that is, which in special environnmental conditions may sometimes, although exceptionally, manifest the tendency to climbing growth. This effect is obtained on plants in which we do not usually meet these phenomena but which, evidently, have the possibility of manifest them provided that am exceptional growth stimulas is operating.

From what above said we can deduce a first and simple work hypothesis, which will be the object of study in the near future, and which prospects the possibility that typically climbing plants owe their behaviour to the capacity of regulating their growth also in consequence of the formation of appropriate quantities of substances with gibberellinlike action and lacking some growth inhibiting condition. The same thing might be true for the plants which are climbing only on exceptional occasions, and a similar possibility might be given to the plant by particular external conditions in which the individual is formed, grows and develops.

Is is interesting also to observe that the analogy between climbing behaviour induced by Gibberellic Acid and natural one, extends also to leaf expansion behaviour and to other characteristics facts included in the field of etiolated plants.

Successive experiments will give us a deeper knowledge of this particular aspect of climbing behaviour and will define the conditions in which movements of shoot apex take place under the action of Gibberellic Acid and structural manifestations inherent, in comparison to those of naturally climbing plants.