Temperature-induced fluorescence changes : a screening method for frost tolerance of potato (solanum sp.)

Field-grown tuber-bearing potatoes were screened for frost tolerance in a late stage of development. Three different clones of Solanum tuberosum L. and two interspecific crosses between clones of S. tuberosum and the wild potato species S. demissum Lindl. were studied. Two different methods were used. (a) Temperature-induced fluorescence changes of intact leaves were measured in freeze-thaw cycles between 20°C and −10°C. The variable fluorescence pattern was characterized in relation to frost tolerance. (b) Controlled freezings of plants in a climate chamber with successively increased low temperature stress, of 1 to 2 hours duration during the dark period. Freezing damages were classified visually.