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.