Effects Of Seed Priming On Drought Tolerance Of Elymus Dahuricus And Elymus Sibiricus

Due to the influence of global climate change,abnormal temperature and extreme weather occur from time to time.Environmental factors,especially irregular precipitation and unpredictable extreme temperature,aggravate the impact on plants.Elymus dahuricus and Elymus sibiricus are the main cultivated species of cultivated variety,which are important components of steppe and meadow,and have high feeding value due to their cold resistance,drought resistance,alkali resistance and sand resistance.In the actual production,the cultivation and utilization of Elymus dahuricus and Elymus sibiricus are difficult due to the low seed germination rate and uneven seedling emergence.Therefore,improving the seed germination rate and seedling uniformity of Elymus dahuricus and Elymus sibiricus have become the main problems for their popularization and utilization.Seed priming,also known as osmotic regulation,is a pre-seeding technique in which seeds are hydrated and dried back to their original weight before radicle protrusion,in preparation for germination.Seed initiation can produce "priming memory",improve seed germination speed and uniformity,improve seed and seedling resistance.In this experiment,Elymus dahuricus and Elymus sibiricus seeds were used as experimental materials.The optimal seed initiation time was determined by seed water absorption curve,respiration rate and storage time after initiation.With water,melatonin(0.1m M,0.2m M,0.4m M),gibberellin(0.01g/L,0.06g/L,0.12g/L),mannitol(1%,3%,5%),PEG(5%,10%,15%)as initiators,the germination test was conducted after 12 hours of initiation and 24 hours of drying.Determination of seed germination rate,germination speed,seedling vigor and other indicators,screening the best initiator and concentration;Drought resistance test was carried out with selected initiator and corresponding concentration.Germination rate,germination rate,seedling activity,content of TP,MDA,activity of CAT and SOD were determined at the seed germination stage.Seedling stage experiment was conducted to determine seedling excavation rate,excavation speed,seedling vigor,total root length,projection area,root surface area,average diameter,ratio of root length to root volume,root volume,root tip number and other indicators,and to explore the effects of seed initiation on seed and seedling drought resistance of Elymus dahuricus and Elymus sibiricus.The main conclusions were as follows:(1)The best initiation conditions of Elymus dahuricus and Elymus sibiricus seeds were as follows: water absorption for 12 hours and redrying for 24 hours at 20℃.(2)Under drought stress,all kinds of initiators promoted seed germination to different degrees,among which 0.06g/L gibberellin had the best effect,which significantly improved seed emergence rate and seedling emergence rate,increased CAT and SOD activities,increased protein content and decreased MDA content of Elymus dahuricus and Elymus sibiricus.(3)Gibberellin 0.06g/L increased root length,projection area,root surface area,average diameter,ratio of root length to root volume,root volume and root tip number,which was beneficial to root growth,water absorption and drought resistance.In conclusion,gibberellin 0.06g/L can improve the drought resistance of Elymus dahuricus and Elymus sibiricus during seed germination and seedling excavation,and provide a seed pretreatment procedure for the emergence and establishment of Elymus dahuricus and Elymus sibiricus in the seeding process.