WATER RELATIONS AND DROUGHT TOLERANCE IN 2 WHEAT-VARIETIES UNDER WATER-STRESS

A drought resistant variety of wheat (Pak-15800) was compared with a susceptible variety (Sarsabz) under water stress and the relationship between leaf water, osmotic, turgor potentials and relative water contents (RWC) were studied. The water stressed plants had lower leaf water potential than control and at a given RWC Pak-15800 had lower water potential than Sarsabz which partly accounts for its better drought resistance. In both the varieties pre-stressed plants maintained osmotic potentials lower than control. In Pak-15800 osmotic potential was significantly lower (-0.06 to -0.11) than Sarsabz. Both control and pre-stressed Pak-15800 plants had higher turgor (0.1 to 0.15 MPa) than Sarsabz at RWC between 65 and 80%. Both pre-stressed and control Pak-15800 had greater elasticity (a lower elastic modulus) than Sarsabz. An understanding of the differences between osmotic and turgor potentials between varieties could be used as a tool in breeding program for wheat.