| 摘要: |
| 【目的】探讨3～4年生柠条（Caragana microphylla Lam.）、沙地柏（Sabina valgaris Ant.）、沙柳（Salix psammophila C.wang et Ch Y.Yang）、白沙蒿（Artemisia sphaerocephala Krasch.）和沙棘（Hippophae rhamnoides Linn.）侧根分支处的抗拉力学特性，为植物固土护坡提供理论基础。【方法】在鄂尔多斯准格尔旗境内和林格尔县境内采集5种植物根系，每种植物采3株标准株，对直径0.5～4 mm的根系按0.5 mm分级，采用织物强力机（加载速度为200 mm/min）测定5种植物各径级根系的室内轴向抗拉力并计算抗拉强度，同时分析根型（鲱骨型、二分枝型）、生长时期（生长季初期（5月）、生长旺盛期（8月））、土壤含水量（0%，6.8%，18.8%，26.6%）对侧根分支处抗拉强度的影响。【结果】5种植物侧根分支处断裂比例均在60%以上，侧根分支处抗拉能力明显不及相邻的直段根；无论是鲱骨型还是二分枝型，5 种植物侧根分支处的抗拉力均低于相邻直段根的抗拉力，柠条、沙柳、沙地柏、白沙蒿和沙棘直段根的抗拉力分别是相邻侧根分支处抗拉力的1.39倍、1.33倍、1.46倍、1.63倍和1.91倍；5种植物2种根型侧根分支处抗拉力和抗拉强度的种间差异相同，均表现为柠条＞沙柳＞沙地柏＞沙棘＞白沙蒿，根型对其影响不显著；生长旺盛期柠条、沙柳、沙地柏、白沙蒿、沙棘侧根分支处抗拉强度均值分别为30.57，18.19，9.52，8.54和5.34 MPa，生长季初期分别为26.79，15.25，10.17，6.76和6.10 MPa，生长时期对5种植物侧根分支处抗拉强度的影响均在α=0.01水平下差异显著；5种植物侧根分支处的抗拉强度均随周边土壤含水量的增大而减小，土壤含水量对其影响显著。【结论】5种植物侧根分支处是根系抗拉的薄弱点，其抗拉力是正确评价植物根系抗拉力学特性的关键。 |
| 关键词: 侧根分支处 直段根 抗拉力 抗拉强度 |
| DOI： |
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| 基金项目:内蒙古自治区自然科学基金重点项目（2010ZD16） |
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| Mechanical properties of tensile at lateral branches of five plants |
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YAO Xi-jun,WANG Lin-he,LIU Jing,et al
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| Abstract: |
| 【Objective】The study discussed tensile mechanical properties at lateral root branches of 3-4 years old Caragana microphylla Lam.,Salix psammophila C.wang et Ch Y.Yang,Sabina valgaris Ant.,Artemisia sphaerocephala Krasch.,and Hippophae rhamnoides Linn.to provide theoretical basis for soil slope protection by plants.【Method】Roots of five plants in ZhunGer and He Lingle,ordos were collected with three standard strains for each plant.The roots with diameters of 0.5-4 mm were graded by every 0.5 mm and the axial tensions of roots in each diameter class were measured using fabric strength machine (load speed of 200 mm/min) to calculate tensile strengths.Then the effects of root type (herring bone pattern and two branching type),growth period (early growing season and growing season),and soil water content (0%,6.8%,18.8%,and 26.6%) on the tensile at lateral branches were analyzed.【Result】Breaking ratios of lateral branches of the five plants were all more than 60%,indicating that the stretch resistance at lateral branch was significantly less than at straight section adjacent.Tensile at lateral branches of the five plants was lower than that at the adjacent straight segments for both the herring bone type and the dichotomous type.The root tensile strengths at the straight section of C.microphylla Lam.,S.psammophila C.wang et Ch Y.Yang,S.valgaris Ant.,A.sphaerocephala Krasch.,and H.rhamnoides Linn.were 1.39,1.33,1.46,1.63 and 1.91 times of tensile strength at the lateral root,respectively.Interspecific differences in the tensile strengths and tensile intensities at lateral branches of five plants and two types were all same in the order of C.microphylla>S.psammophila>S.valgaris>H.rhamnoides>A.sphaerocephala.Root type had no significant effects.At the vigorous growth period, the mean values of tensile strength of lateral root branches for C.microphylla,S.psammophila,S.valgaris,H.rhamnoides,and A.sphaerocephala were 30.57,18.19,9.52,8.54 and 5.34 MPa,while at the early growing season, the values were 26.79,15.25,10.17,6.76 and 6.10 MPa,respectively.The effects of growth period on tensile strength of lateral root branches among the five plants were significant (α=0.01).The tensile strengths of lateral root branches of the five plants decreased when the soil moisture increased and the influence of soil moisture was significant.【Conclusion】The lateral root branches of the five plants were vulnerable in tensile resistance of the root system,and their tensile resistances were key to accurately evaluate mechanical properties of plant roots. |
| Key words: lateral root branch straight section root anti-tension tensile strength |
