Evaluation of genetic variability in potato cv. 'Parda-Pastusa' obtained through the physical mutagenic agents

'Parda-Pastusa' is probably the most important variety of potato in Colombia. Its susceptibility to frost and Phytophthora infestans can cause important losses in the crop. In order to induce genetic variability to select clones resistant to frost and late blight, disease-free micropropagated plantlets, obtained from meristem culture of indexed tubers were irradiated with gamma rays from a 60Co source. Virus-free mericlones were initially irradiated with 0,25, 50, 75 and 100 Gy or with 0, 10, 20 and 30 Gy. The optimal radiation dose was found to be 20 Gy. A mass propagation was carried out, and plantlets were irradiated with the optimal radiation dose. Clones derived from irradiated material were propagated for selection under simulated frost conditions (-7 deg. C for 360 minutes) and co-cultured with extracts of fungus, Phytophthora infestans. The selected clones will be transferred to field conditions for evaluation of agronomic and genetic characteristics. (author). 1 ref