Metabolic changes in wheat plants subjected to a water-deficit stress programme

Wheat plants (Triticum durum cv Adamello) were grown in a controlled environment. In one set, control plants were regularly watered; the other set of plants was subjected to a three-cycle water stress programme obtained by withholding water and rewatering to field capacity at the end of each cycle. The water and osmotic potentials of the stressed leaves were always lower than in the control; and although the turgor potential decreased, it remained at positive values. After the first period of stress, water-deficit conditions led to a reduction in the modulus of elasticity and an increase in solute leakage. During the whole stress programme, total lipids decreased and the unsaturation level did not change. Phospholipids, glycolipids and sterols decreased only after the first stress period, whereas the free fatty acid contents increased in the stressed plants during the whole stress programme. Free radical production was greater in the stressed plants only following the first period. After the first and third stress periods, malondialdehyde contents decreased in comparison to the control; on the contrary, the lipid extracts of unwatered plants showed an increased inhibition of linoleic acid oxidation. Water-deficit conditions either maintained at the same level or increased superoxide dismutase and catalase activities. © 1993.