Tuberization in potato at high temperatures: Responses to gibberellin and growth inhibitors

The responses of potato plants (Solanum tuberosum L., cv. Sebago) to high temperatures (32 day/28 C night or 32/18 °C) and gibberellin are similar, in that they promote haulm growth and suppress tuber production, whereas low temperatures (22/18 °C) abscisic acid and CCC have the opposite effect, promoting tuber production and reducing the growth of the haulms. The inhibitory effect of the high temperatures on tuber production, under a photoperiod of 14 h, was almost completely reversed in these experiments by the application of CCC, and partly reversed by ABA. Single-leaf cuttings from plants grown at the various temperatures and chemical treatments responded in the same way as the whole plant. It is suggested that both haulm growth and tuber initiation are influenced by a common hormonal control, and that temperature exerts its influence by altering the balance between the levels of endogenous gibberellins and inhibitors. These substances apparently act directly on the stolon tip, rather than through their general influence on haulm growth