寒旱环境盐胁迫条件下两种草本植物的根系力学特性研究

摘要

Two species (Elymus nutans Griseb. and Agropyron trachycaulum (Linn.) Gaertn.) which are adaptive to the climate of the Xining Basin and the surrounding areas were taken as the test species. Through interior cultivation method, salt stress test was applied to the two species by Na2SO4 solution with the concentration gradients of 50 mmol/L, 100 mmol/L, 150 mmol/L and 200 mmol/L. After being given salt stress treatment, on the 15th day, 30th day and 45th day, the single root tensile resistance and single root tensile strength of the two species were measured respectively. The test result exhibits: under the same salt stress, as the growth period increased, the tensile resistance of single root of two herbs gradually increased too, while the tensile strength of single root decreased gradually; with the same growth period, as the Na2SO4 concentrations increased from 0 mmol/L to 200 mmol/L, the tensile resistance of single root of two herbs gradually decreased; furthermore, at the same salt stress and the same growth period, the single root tensile resistance and tensile trength of Agropyron trachycaulum was 0.008-0.025 N and 9.646-72.807 MPa, which are higher than those of Elymus nutans Griseb.; the relationship between single tensile resistance and root diameter of 2 herbs was exponential function; the tensile strengths of single root for 2 herbs decreased with the increasing of root diameter, and both had power function relationship with root diameter. This study has theoretical value in further exploring characteristics and variation law of mechanical properties of herbaceous roots under salt stress in cold and arid environment. Besides, the study has practical significance in preventing and controlling geological disasters in the study area, such as soil erosion, shallow landslide.%选取适宜于西宁盆地及其周边地区生长的2种优势草本植物垂穗披碱草(Elymus nutans Griseb.)和细茎冰草(Agropyron trachycaulum(Linn.)Gaertn.)作为试验供试种,通过室内种植培育方式,采用浓度梯度分别为50 mmol/L、100 mmol/L、150 mmol/L、200 mmol/L的Na2SO4溶液对2种植物进行盐胁迫处理.在盐胁迫试验处理后的第15 d、30 d和45 d,分别测定2种植物单根抗拉力和单根抗拉强度.结果表明:相同盐胁迫浓度时,2种植物单根抗拉力随生长期增长而逐渐增大,单根抗拉强度随生长期增加而逐渐降低;相同生长期,2种植物单根抗拉力随着胁迫液浓度由0 mmol/L增加至200 mmol/L时,表现为逐渐减小趋势;进一步研究表明,在相同胁迫浓度和相同生长期条件下,细茎冰草单根抗拉力和单根抗拉强度分别较垂穗披碱草高0.008～0.025 N和9.646～72.807 MPa;2种草本植物单根抗拉力与根径之间呈指数函数关系;2种草本单根抗拉强度分别随根径的增加而逐渐减小,且均与根径呈幂函数关系.研究成果对于进一步探讨寒旱环境盐胁迫条件下,草本植物根系力学强度特征及其变化规律具有重要理论价值,同时对于有效防治研究区水土流失、浅层滑坡等地质灾害的发生具有实际指导意义.