The Geographic Variations And Study On Adaptability In Reproduction And Growth Characteristics Of Leymus Chinensis In Songnen Saline-alkali Grassland

Songnen salinization is an important influence on grassland ecosystems in arid and semi-arid regions of the world,currently,the global saline-alkali land area is about 1billion square kilometers.Seed dormancy and germination,morphological and reproductive characters of plants under saline-alkali environment will produce certain ecological adaptation characteristics.The same plant has been growing in a heterogeneous environment for a long time,using natural selection has produced a wide range of genetic variation and rich genetic diversity within the species,at the same time,due to genetic drift,mutation,migration and other factors within the species,the same species in different geographical locations have significant differences in morphological and physiological characteristics.In-depth systematic study of the geographic variation patterns of seed reproduction and growth traits of saline meadow plants is important for the successful restoration of vegetation in degraded meadow ecosystems.We took Leymus chinensis as the research topic,and field investigation and sampling,indoor simulation and analysis were carried out on Leymus chinensis in the saline-alkaline land of Songnen Plain.We also systematically studied seed propagation of Leymus chinensis in different geographical areas in temperature（16/28°C,5/28°C,5/35°C）,salinity（Na₂CO₃:0m M,5 m M,10 m M,25 m M;Na Cl:0m M,10 m M,20 m M,50 m M,100 m M,200m M;Na HCO₃:0m M,10 m M,20 m M,50 m M,100 m M,200m M）and morphological characters of Leymus chinesis in different geographical areas.The genetic and environmental factors responsible for these variations were investigated through long-term localization experiments such as soil column displacement and common garden experiments.The result showed that The 1000-seed weight,seed length and seed width differed significantly among the different provenances in the field.The highest 1000-seed weight of Leymus chinensis was 2.63g in Fuyu,the lowest 1000-seed weight of Leymus chinensis was 1.6g in Qianan.The highest seed length was 8.43mm in Fuyu,the lowest was 5.52mm in Qianan.The highest seed width of Leymus chinensis was 1.15mm in Changling,the lowest seed width of Leymus chinensis was1.05mm in Changlingxi.The1000-seed weight coefficient of variation was between 2.90%-16.2%,the seed length coefficient of variation was between 6.50%-16.71%,the seed width coefficient of variation was between 7.42%-11.33%.Correlation analysis showed that 1000-seed weight correlated to the seed length and width.Plant height of Leymus chinensis differed significantly among the different provenances in the field.The highest plant height of Leymus chinensis was 57.5cm in Wulanhaote,the lowest plant height was27.5cm in Changling,the coefficient of variation for plant height was between 10.27%-23.92%.Correlation analysis showed that tiller correlated to the leaf width,plant height correlated to the p H.The germination rate of Leymus chinensis was more than 50%at 16/28℃.The highest germination rate was 82%in Daqing,there was no significant difference for seedling length and root length.There was significant difference on germination rate at5/28℃,The highest germination rate is 76%in Jiangjiadian,there was significant difference on seedling length and root length.There was significant difference on germination rate at 5/35℃,but no significant difference on seedling length and root length.The seed germination rate,seedling growth and root length of Leymus chinensis decreased from different provenances with the increase of salt concentration（Na₂CO₃、Na Cl、Na HCO₃）.Compared with other provenances,the seed germination of Leymus chinensis was significantly affected by the change of Na₂CO₃ concentration,and the germination rate was 0 at 25m M Na₂CO₃.The germination rate of Leymus chinensis for Qian an was 0 at 200m M under Na Cl stress,but it has highest germination rate at other concentration gradients.The seed germination rate of Changling and Changlingxi was more than 15%at each concentration gradient under Na HCO₃ stress,the seed germination rate of Leymus chinensis for Qianan,Fuyun and Lindian were close to 0 at100m M Na HCO₃.The plant height,leaf length and leaf width differed significantly among the different provenances in the soil column displacement.The highest plant height of Leymus chinensis was 85.3cm in Zhenlai,the highest leaf length was 25.0cm in Qianan,the highest leaf width was 8.54mm in Wulanhaote,there was no significant effect on tiller.The plant height coefficient of variation was between 4.36%-17.49%,the leaf length coefficient of variation was between 6.37%-24.24%,the leaf width coefficient of variation was between 7.69%-17.29%.The leaf length and leaf width differed significantly among the different provenances in the common garden.The highest leaf length of Leymus chinensis was 31.1cm in Qianan,the highest leaf width of Leymus chinensis was 9.52mm in Wulanhaote.The leaf length coefficient of variation was between 1.31%-16.14%,the leaf width coefficient of variation was between 5.47%-26.0%.Biomass,specific leaf area,proline,soluble sugar and chlorophyll of Leymus chinensis had no significantly difference under the soil column displacement and common garden treatment.The results of our study have revealed that the 1000-seed weight,seed length and width,spike length and seed-set rate differed significantly among the different provenances in the field.1000-seed weight correlated to the seed length and width.Seeds of Leymus chinensis from different provenances showed significant differentiation in germination rate and root seedling length after different environmental changes and salt-alkali stresses by long-term environmental adaptation.The transplanted Leymus chinensis were removed to the soil column and common garden eliminated the influence of environmental factors such as temperature and precipitation,its phenotypic characteristics were still significantly different among provenances due to long-term soil environment.These findings illuminate adaptive mechanisms of reproduction and growth traits of Leymus chenensis.It provided a theoretical and practical reference for leymus chinensis how to adapt to climatic change in the future.