COLD-ACCLIMATION IN CULTIVARS OF AVENA-SATIVA

Changes in frost resistance and contents of total carbohydrate, free p roline and soluble protein in response to cold were studied in two win ter cultivars of Avena sativa (cvs America and OT 220 x Omihi) with di fferent survival capacities under field conditions. Changes in polar l ipids and their constituent fatty acids were studied in cv OT 220 x Om ihi. The lowest frost resistance was found in cv America, as observed in the field. Both cultivars increased their frost resistance and tota l carbohydrates, free proline and soluble proteins during cold acclima tion. Some polar lipids (monogalactosyldiacylglycerols, digalactosyldi acylglycerols and phosphatidylinositol) increased after low temperatur e conditions in the more frost resistant cultivar. Unsaturated fatty a cids (linoleic and linolenic) increased in some lipid fractions in col d acclimated cv OT 220 x Omihi. Genetic variability between the two cu ltivars and possible frost resistance mechanisms are discussed.