Propagation and in vitro tuberization of two varieties of potato nork Araque Barrera, Eyda Johanna, Bohórquez Quintero, María de los Angeles, Pacheco Díaz, José Estiben, Correa Mora, Lenny Yojana, Urquijo Ruiz, Johan Sebastian, Castañeda Garzón, Sandra Liliana, Pacheco Maldonado, José Constantino