小麦抗倒伏免疫反应的力学仿真及机理探究

Mechanical simulation and mechanism of immune response of wheat to lodging

【目的】探讨小麦镇压后麦秆基部弯曲及采用化控措施使麦秆基部变短变粗的抗倒伏免疫反应的作用机理,分析其对小麦抗倒伏能力的影响,为指导小麦抗倒伏栽培和育种提供参考。【方法】通过Fluent软件,在模拟群体小麦风载效应的基础上,建立底端固定、顶端自由的单株活体小麦在风雨自重荷载作用下的结构整体非线性有限元分析模型,考虑风向及茎秆发育的随机性,沿360°方向逐个扫描施加风载,以未经任何处理的直秆小麦为基准进行小麦抗倒伏仿真计算,对比分析化控措施处理的直秆小麦、镇压或倒伏后基部弯曲小麦的临界弯距和最大位移,探讨弯扭组合、节间长度和茎秆变截面对圆柱壳临界弯矩的影响。【结果】与未经任何处理的直秆小麦相比,化控措施处理直秆小麦的屈曲临界荷载提高了27.9%,而基部弯曲小麦屈曲临界荷载提高了43.7%~98.9%;化控措施处理直秆小麦的最大位移减小了9.1%,基部弯曲小麦的最大位移减小了11.7%~21.3%。弯扭组合作用下的临界弯距是弯矩单独作用下的2.23~2.64倍,节间长度变短0.95 cm时小麦茎秆的临界弯距提高了9.8%。在单独轴力和纯弯距作用下,变截面茎秆的临界弯距较非变截面茎秆分别提高15.9%和13.1%。【结论】小麦抗倒伏免疫反应的机理是茎秆基部弯曲和变粗、变短提高了茎秆的局部稳定性,从而增强了小麦的整体稳定性即抗倒伏能力。

【Objective】Aiming at the mechanism of immune response of wheat to lodging related to the bending of wheat base stem due to rolling and the shortening and thickening of wheat base stem caused by chemical control measures,this study investigated the immune response of wheat against lodging to more effectively guide the cultivation and breeding of lodging-resistant wheat.【Method】The Fluent software was used to simulate effect of wind load on wheat and a single nonlinear finite element analysis model of wheat was established with a fixed bottom and free top under the actions of wind load,rain load,and deadweight.Considering the randomness of wind direction and stem development,the wind load was applied in 360°directions by scanning.The effects of bending-torsion combination,internode length and variable section of stem on the critical moment of cylindrical shells were also discussed.【Result】The critical moment load of the straight wheat stem treated with chemical control measures was increased by 27.9%,whereas that of the bent wheat base stem due to rolling or lodging was increased by 43.7%-98.9%.The maximum displacement of the straight wheat stem treated with chemical control measures was reduced by 9.1%,whereas that of the bent wheat base stem due to rolling or lodging was reduced by 11.7%-21.3%.The critical moment of wheat stalks under bending-torsion combination was 2.23-2.64 times of that under bending moment alone.When the internode length was shortened by 0.95 cm,the critical moment of wheat stalks increased by 9.8%.The critical moment of stalks with variable cross-section was 15.9%and 13.1%higher than that of non-variable cross-section stalks under single axial force and pure bending,respectively.【Conclusion】The mechanism underlying the immune response of wheat to lodging was that the bending and shortening of the wheat base stem increased the thickness of the wheat base stem,thus improved the local stability of the wheat stem.