Seed dormancy and germination response of Aegilops tauschii to exogenous application of GA3 and warm water.
The invasion of Aegilops tauschii has seriously threatened the wheat production in China. The seeds of A. tauschii display obvious dormancy. In present study, seed dormancy and germination of A. tauschii were investigated by treating seeds with exogenous GA3and different hot water treatments. The results revealed that exogenous GA3and warm water soaking treatments were beneficial to dormancy breaking and germination of seeds. Among all treatments, 500 mg.L-1GA3 for 24 h and hot water treatments with 45°Cwarm for 5 min significantly improved germination. During germination, SOD activity in seeds treated with GA3(500 mg.L-1) and warm water (45°C) increased significantly. Increased SOD activity reduced the degree of oxidative damage of plasma membrane and resulted a continuous decrease in thiobarbituric acid reactive substance assay (TBARS) content. Thereby, seeds were prompted to develop in a direction conducive to germination. In addition, GA3(500 mg L-1) and warm water (45°C) treatments increased the endogenous levels of gibberellin (GA3), auxin (IAA), and zeatin riboside (ZR), and decreased the endogenous ABA in seeds. This had resulted significantly higher ratios of GA3/ABA, IAA/ABA and ZR/ABA than those ratios of distilled water (room temperature) treated plants. The effect eventually promoted the germination of E. ulmoides seeds. Based on the changes in enzyme activity and endogenous hormones during seed germination, it is concluded that 500 mg.L-1GA3 for 24 h and hot water treatments with 45°Cwarm for 5 min significantly improved germination of A. tauschii seeds.