Study On Saline-alkali Tolerance And Soil Consolidation And Slope Protection Ability Of Four Herbaceous Plants

Oenothera biennis,Perilla frutescens,Echinops davuricus and Lychnis fulgens are all herbaceous plants that can grow in the cold regions of northern China,with strong adaptability and resistance and ornamental value.In this experiment,these 4 herbaceous plants were used as test materials,and the neutral salt Na Cl and alkaline salt Na HCO₃were mixed at molar ratio of 1:1.Stress was carried out at 0,25,50,75 and 100 mmol/L in seed germination stage,and at0,50,100 and 200 mmol/L in seedling stage.The saline-alkali tolerance of the 4 herbaceous plants at these 2 growth stages was evaluated comprehensively.In addition,the soil consolidation and slope protection ability of 4 species under complex saline-alkali stress was studied by single root tensile test,pullout test and scouring test.The main research results are as follows:（1）The germination percentage,germination potential,germination index,vitality index and radicle length of the sprouts of the 4 herbaceous plants decreased gradually with the increase of the concentration of the mixed saline-alkali solution.The decrease amplitude of different plants was different,and the inhibition of seed germination was different.（2）The biomass of the 4 herbaceous plants decreased gradually with the increase of the concentration of the mixed saline-alkali solution,and the ground diameter growth of the Oenothera biennis and the plant height growth of the Echinops davuricusr at the concentration of 50 mmol/L were increased compared with the control.Leaf water potential decreased significantly,while relative electrical conductivity and MDA content increased significantly.CAT activity increased first and then decreased.The contents of soluble protein and proline gradually decreased and increased,respectively.Photosynthetic parameters Pn,Gs and Tr of the 4 herbaceous plants decreased gradually.The contents of chlorophyll a,chlorophyll b and carotenoid showed a decreasing trend.（3）Through comprehensive evaluation,the order of saline-alkali tolerance of the seeds of the 4 herbaceous plants at seed germination stage was as follows:Echinops davuricus>Lychnis fulgens>Perilla frutescens>Oenothera biennis.The order of saline-alkali tolerance at seedling stage was as follows:Echinops davuricus>Lychnis fulgens>Oenothera biennis>Perilla frutescens.The saline-alkali tolerance of Echinops davuricus was the strongest both at seed germination stage and seedling stage,followed by Lychnis fulgens.（4）The total number of roots,total root length,total root surface area and total root volume of the 4 herbaceous plants decreased gradually with the increase of the concentration of mixed saline-alkali solution.The root structure types of the four herbaceous plants were divided into two types:Oenothera biennis and Echinops davuricus were R type,Perilla frutescens and Lychnis fulgens were M type.（5）With the increase of the concentration of mixed salt-alkali solution,the single root tensile resistance,tensile strength,elongation and root pulling resistance of the 4 herbaceous plants decreased,and the effect on enhancing soil scourability was also gradually weakened.The single root tensile resistancet increased with the root diameter as a power function,but the tensile strength and elongation had no significant correlation with the root diameter.According to the pulling resistance and soil anti scourability index,it was found that the soil reinforcement and slope protection ability of Lychnis fulgens and Perilla frutescens were better than that of Oenothera biennis and Echinops davuricus.