Before sprouting, potato tubers pass through a period of dormancy which has an specific time for each variety. When the conditions are suitable for tuberset, stolon elongation stops and swelling starts between two last nodes of each stolon. Many factors are involved in this process, but an important and coordinated action between hormones is proposed. Cytokinins levels in both S. tuberosum L. varieties ICA-Única and Tuquerreña and S. phureja Juz. et Buk. var. Criolla Colombia were quantified during different stages of tuber development: 00 - potato tuber in stage of dormancy; 03 - tubers in break dormancy with buds between 2 to 3 mm of length; and 40 - initiation of tuber formation; swelling and duplicating initial diameter. Cytokinins were extracted by Thin Layer Chromatography, detection and quantification were carried out by cotyledon radish weight (Raphanus sativus) bioessay. In the species S. tuberosum L. var. Tuquerreña (late variety) the cytokinins were absent and, in the early variety ICA-Única were statistically higher in the stage 03, when initiate the filled of the tuber. Finally, in the early species S. phureja Juz. et Buk. variety Criolla Colombia, cytokinins were significant in the stage 00 and 03, with an evident increase in the last one. Our results indicate a strong relationship between cytokinins and tuber break dormancy: cytokinins were present in early varieties and absent in the late one.
Cytokinins; Tuberization; Solanum tuberosum L.; Solanum phureja Juz. et Buk
