Wheatgrass Germination and Seedling Growth under Osmotic Stress

Osmotic stress is one of the major environmental stresses that limits plant growth and seed germination in many areas of the world. The purpose of this research was to determine the degree and range of tolerance to osmotic stress in 20 wheatgrass ecotypes to identify ecotypes that might be potentially useful in arid and semiarid regions. We used a completely randomized factorial design with two factors, five levels of osmotic stress (0, -0.2, -0.5, -0.8, and -1.6 MPa), wheatgrass ecotypes, and three replicates. Our findings suggest that AD1, AD2, AD3, and AD5 ecotypes under osmotic stress have a higher level of final germination percentage (FGP) and rate of germination (GR), although they had a lower value for the average germination time (MGT) than other ecotypes during the experiment. These results suggested that AD1, AD2, AD3, AD5, AE5, AC6, and FA ecotypes exhibited a more effective protection, along with various mechanisms, and the mitigation of oxidative damages such as lipid peroxidation through mechanisms by which enzymatic and non-enzymatic antioxidant activities were maintained at a higher level. Also, these ecotypes showed higher proline and total nonstructural carbohydrate contents (TNC), but lower malondialdehyde content (MDA) and H2O2 content than other ecotypes. A cluster analysis found these same six ecotypes (AD1, AD2, AD3, AD5, AE5, and AC6) and FA were clustered into a group of "osmotic-tolerant ecotypes". This group might be potentially useful in arid and semiarid regions.