Abstract:In the present study,with two pot-cultured winter wheat cultivars, Qinmai No. 3 and Jinan No. 13,that differ in sensitivity to drought,the effect of drought on the lipid composition of root cell was investigated. Drought was created by withholding water. After 6 days of stress,the content of total acyl lipids measured as total fatty acids and the double bond index of membrane lipids were decreased. Drought stress also decreased phospholipid content drastically,but the relative distribution of individual phospholipids was constant and independent of stress. Free sterol content increased in response to stress. As a consequence the ratio of free sterol/phospholipid increased from 0. 050 and 0.051 of the control to 0. 147 and 0. 120 of the treatment,respectively for cultivars Qinmai No. 3 and Jinan No. 13. These results suggest that root cell membranes of winter wheat seedings respond to drought stress by reducing the degree of lipid fluidity, which would reduce the permeability of the plasma membrane to small molecular substances and help to maintain cell rigidity.