中文摘要：

以3-4年生并处于生长旺盛期的柠条、沙柳、沙棘和白沙蒿为研究对象,采用自制夹具、TY8000伺服强力机,对有生命力的、根径为1-4 mm的侧根分支处及其相邻上级直根的抗折力进行测定,分析4种植物侧根分支处与相邻上级直根抗折力、抗折强度的差异.结果表明：尽管4种植物各径级侧根分支处平均根径大于相邻上级直根的平均根径,但侧根分支处的抗折力和抗折强度均小于相邻上级直根的抗折力和抗折强度;柠条、沙柳、沙棘和白沙蒿的侧根分支处抗折强度分别为相邻上级直根的71.5%、62.9%、45.4%、35.4%.4种植物侧根分支处、相邻上级直根的抗折力与根径呈显著的幂函数正相关,抗折强度与根径呈显著的幂函数负相关;4种植物侧根分支处、相邻上级直根抗折强度大小均为：柠条（33.66、47.06 MPa）〉沙柳（17.31、27.54 MPa）〉沙棘（3.97、8.75 MPa）〉白沙蒿（2.18、6.15 MPa）.

英文摘要：

Taking four plant species,Caragana korshinskii,Salix psammophila,Hippophae rhamnides and Artemisia sphaerocephala,which were 3-4 years old and in vigorous growth period,as test materials,the anti-fracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateral-root branches were vital and the diameters were 1- 4 mm. The results showed that the anti-fracture force and antifracture strength of lateral-root branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateral-root branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii,62.9% for S. psammophila,45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants,the anti-fracture force positively correlated with the diameter in a power function,while the anti-fracture strength negatively correlated with diameter in a power function. The anti-fracture strengths of lateral-root branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii（ 33.66 and 47.06 MPa） 〉S. psammophila（ 17.31 and 27.54 MPa） 〉H.rhamnides（ 3.97 and 8.75 MPa） 〉A. sphaerphala（ 2.18 and 6.15 MPa）.