The control of tuberization in potato (Solanum tuberosum L.) at high temperatures

Abstract

Potato production in the warm, humid lowland tropics is linited by the fact that tuber formation is more or less completely prevented by high temperatures. The work reported here was aimed at understanding the physiological basis of the temperature effect on growth and tuberization in potato, in the hope that this information might indicate means by which the plant could be manipulated to produce tubers in warm environments. High day and night temperatures suppressed tuber formation in intact plants ( cv. Sebago) grown under short days, and in apical, 2-node and single-node cuttings excised from them and grown under mist propagation under long days. These results suggest that temperature regulatee tuberization directly via a tuberizing stimulus acting at the stolon tip rather than by influencing haulm growth and assimilate competition. The responses of cv. Sebago to high temperatures (32/18oC or 32/28oC) and GA are similar, in that they promote haulm growth and suppress tuber production, whereas low temperatures (22/18oC), ABA and CCC have the opposite effect, promoting tuber production and reducing the growth of the haulms. The inhibitory effect of high temperatures on production (under a 14h photoperiod) was almost completely reversed in these experiments by 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 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.