LAUSR

Sprouts of potato tubers were excised from the three potato cultivars Agria, Hermes, and Spunta, sterilized and subjected to shoot formation and propagation on Murashige and Skoog (MS) medium supplemented with 1 mg dm-3 6-benzylaminopurine (BAP) + 0.5 mg dm-3 gibberellic acid. Shoots were rooted on MS medium supplemented with 1 mg dm-3 indole-3-butyric acid. To increase shoot vigour prior tuber formation, shoots were subcultured on MS medium supplemented with 0.56 mg dm-3 BAP, 0.11 mg dm-3 2,4-dichlorophenoxyacetic acid, and 0.96 mg dm-3 naphthaleneacetic acid. Under dark, microtuberization on MS media supplemented with 4 mg dm-3 of both BAP and kinetin was better than 4 mg dm-3 BAP alone, where they induced higher number of microtubers per shoot and/or the percentage of shoots that formed microtubers. The highest frequency of microtuber formation was achieved when sucrose at high concentration (8 %) was used as carbon source in culture media. Glucose ranked at the second position whereas fructose reduced the microtuber formation frequency when it was used alone or in combination with glucose. Under the applied culture conditions, cvs. Agria and Hermes showed better micropropagation and microtuberization in comparison to cv. Spunta. In addition, isozyme and RAPD techniques revealed that Agria and Hermes are closer to each other when compared with the third cultivar.