ANALYSIS OF COLD RESISTANCE IN WILD AND CULTIVATED POTATO SPECIES

We have analyzed freezing tolerance and capacity to acclimate to cold in wild, uncultivated Solanum species and cultivated varieties of Sola num tuberosum. Wild Solanum species, S. acaule, S. sogarandinum, S. mu ltidisectum and S. polyadenium were obtained from the single seeds of each species and cultured in vitro. Cultivated varieties, Bzura, Cisa, Glada, Grot, Ibis, Lotos, Dunajec and Orlik were cultured in vitro fr om the single seed tubers. The studies were conducted with unhardened plantlets, cold hardened for 12 days at 4 degrees C and deacclimated f or two days. The freezing tolerance was determined by the conductivity method. The results showed that all of the wild species were freezing resistant in the unhardened state with LT(50) of -2.0 to -4.5 degrees C. During cold hardening at 4 degrees C for 12 days the wild potato s pecies, S. acaule, S. sogarandinum, and S. multidisectum developed the ir freezing resistance to T-50 of about -9.0 degrees C, while S. polya denium only barely increased its freezing resistance, to -4.0 degrees C from -2.0 degrees C. The cultivated potato varieties were cold sensi tive before hardening (LT(50) of about 0 degrees C) and they displayed only insignificant increase in frost resistance to LT(50) of -1.5-2.0 degrees C after chilling. After deacclimation all the species display ed decreasing in freezing tolerance, however, the level was higher tha n that of the unhardened plants. Based on the results obtained, the an alyzed potatoes might be classified into three different groups with r egard to freezing tolerance. The first group was freezing resistant an d able to acclimate to cold after chilling (S. acaule, sogarandinum, a nd S. multidisectum), the second one was freezing resistant, but unabl e to cold acclimate (S. polyadenium) and the third group was freezing sensitive and unable to cold acclimate (all the cultivated varieties).