Grasses represent the most productive and widely grown crop family across the globe but are susceptible to structural failure (lodging) during growth (e.g., from wind). The mechanisms that contribute to structural failure in grass stems are poorly understood due to a lack of systematic studies of their biomechanical behavior. To this end, this study examines the biomechanical properties of sweet sorghum (Sorghum bicolor (L.) Moench), focusing on the time-dependent behavior of the stems. Specifically, we conducted uniaxial compression tests under ramp and creep loading on pith and stem specimens of the sorghum cultivar Della. The tests demonstrated significantly nonlinear and time-dependent stress-strain behavior in all samples. We surmise that this behavior arises from a combination of poroelasticity due to migration of water through the plant and viscoelasticity due to rearrangement of macromolecular networks, such as cellulose microfibrils and lignin matrices. Overall, our measurements demonstrate that sorghum is not a simple reversible elastic material. As such, a complete understanding of the conditions that lead to stem lodging will require knowledge of sorghum's time-dependent biomechanical properties. Of practical importance, the time-dependent biomechanical properties of the stem influence its mechanical stability under various loading conditions during growth in the field (e.g., different wind speeds).

草是全球产量最高，生长最广泛的农作物家族，但在生长过程中（例如因风吹袭）易受结构破坏（倒伏）的影响。由于缺乏对其生物力学行为的系统研究，人们对导致草茎结构破坏的机制了解甚少。为此，本研究研究了甜高粱（高粱）的生物力学特性。（L.）Moench），着重研究茎的时间依赖性行为。具体来说，我们对高粱品种Della的茎和茎标本在斜坡和蠕变载荷下进行了单轴压缩试验。测试表明，所有样品均具有明显的非线性和随时间变化的应力应变行为。我们推测这种行为是由于水通过植物迁移引起的孔隙弹性和由于高分子网络（例如纤维素微纤维和木质素基质）的重排而产生的粘弹性的结合。总体而言，我们的测量结果表明，高粱不是简单的可逆弹性材料。因此，要全面了解导致茎倒伏的条件，就需要了解高粱随时间变化的生物力学特性。具有实际意义