Effects of Water Stress Induced by Polyethleneglycol-6000 the Seed Germination and Seedling Growth of Switchgrass

The seed physiological qualities of three switchgrass ecotypes(Panicum virgatum L.) were evaluated in laboratory by the simulation of water potentials using polyethyleneglycol-6000(0.0,-0.2,-0.4,-0.6,-0.8 and-1.0 MPa).The physiological indices including germination percentage,normal seedlings,ungerminated fresh seeds,dead seeds,germination index,seed vigor index,root length,shoot length and leaf area were measured.Results showed that the seed germination percentage,germination index,vigor index and seedling growth indexes of three switchgrass varieties increased under water stress,while the normal seedlings rate significantly decreased with osmotic potential decreasing.Fresh ungerminated seeds increased significantly,and dead seeds also increased compared to control.However,there was no significant difference among treatments.These results indicated that the secondary dormancy of switchgrass seed was induced in the treatment of lower osmotic potential.The effects of water stress on seed germination and seedling growth was severe when osmotic potential was below- 0.4 MPa.The adaptability and resistance of switchgrass to water stress differed between tested cultivars.The adaptabilities of three switchgrass ecotypes to water stress were ordered as Alamo(lowland) Cave-in-Rock(intermediate) Sunburst(upland).