Effects of Different Seed Treatments on the Threshold of Water Potential during the Seed Germination of Switchgrass

In order to provide theoretical basis for sowing and seedling establishment under drought condition,the drought resistance and water requirement of switchgrass were investigated at germination and seedling establishment stages.The seeds of different switchgrass species(Pathfinder,Traiblazer and Alamo) were treated with low temperature(4℃) and 8 M sulfuric acid under different PEG concentrations(-0.1~-0.5 MPa).The water requirement thresholds of switchgrass seeds were evaluated at radicle emergence,plumule emergence and seedling establishment stages.Results showed that the times required for achieving the 50%radicle emergence,plumule emergence and seedling establishment of all seeds increased with environmental water potential decreasing.Water requirement threshold at seedling establishment stage was higher than that at radicle emergence and plumule emergence stages.Both low temperature treatment(4℃) and 8 M sulfuric acid treatment shorten the times required for achieving the 50%radicle emergence,plumule emergence and seedling establishment of all tested seeds,and enhanced the water requirement threshold in each stage.Pathfinder variety had lower requirement for environmental water potential than Trailblazer and Alamo varieties under the same treatment.Therefore,seedling establishment stage was the most sensitive to ambient water stress.Pathfinder variety showed the highest stress tolerance and drought resistance among three varieties.