The Adaptability Of Seed Germination And Seedling Establishment Of Stipa Breviflora In Different Populations

Appropriate seed provenance is the key point to ensure long-term sustainability in ecological restoration of degraded grassland.Seed germination and seedling establishment,the important stages in plant life history,are vital bases for seed provenance selection.Stipa breviflora is an important native grass species with potential utilization value in ecological restoration of degraded grassland due to its strong drought resistance and adaptability.In this study,we selected 14 Stipa breviflora populations located along latitude gradient and performed field investigation,lab seed germination and field emergence experiments in two consecutive years.The main findings are as follows:1.Field investigation experiment showed that there was significant variation in growth and reproduction traits of Stipa breviflora in different populations(P<0.05).Overall,with latitude increasing,seed yield per individual,plant height and number of reproductive shoots per individual had decreasing trends,while shoot diameter had increasing trend.And there was no significant relationship between latitude and other traits.2.Lab germination experiment showed that there was significant variation in germination percentage under different germination conditions(temperatures and water potentials)and between different seed collection years(P<0.05).Under different temperature conditions,except for 20/30℃,there were positive relationships between latitude and germination percentages under 5/15℃,10/20℃ and15/25℃.Under different water potentials,except for-0.6MPa,there were positive relationships between latitude and germination percentages under-0.2MPa and-0.4MPa.Moreover,dry storage can break physiological dormancy of Stipa breviflora and improve germination percentage.3.Field emergence experiments were respectively performed in Yuzhong,Gansu and Alxa,Inner Mongolia.There was significant variation in seedling emergence and seedling survival of Stipa breviflora in populations,while no significantly variation in seedling overwintering.Seedling emergence in Yuzhong and Alxa was positively related to latitude.However,the relationship between seedling survival and latitude varied with field sites.In Yuzhong,seedling survival was negatively related to latitude.In Alxa,seedling survival was positively related to latitude.There was no relationship between seedling overwintering and latitude.4.The results of redundancy analysis and structural equation showed that lab germination percentage was positively related to field seedling emergence,while the relationship between germination percentage and field seedling survival varied with field sites.Overall,for fresh seeds,germination percentage at-0.2MPa and 5/15℃ had a better indication on field seedling emergence.For stored seeds,germination percentage at 15/25℃ and 10/20℃ had a better correlation with field seedling emergence.