Department of Horticulture, Estación Experimental La Mayora (CSIC), Algarrobo-Costa 29750, Malaga, Spain;
Am J Bot. 2004 Mar;91(3):352-60. doi: 10.3732/ajb.91.3.352.
We report the biomechanics and anatomy of fruit wall peels (before and after cellulase/pectinase treatment) from two Lycopersicon esculentum cultivars (i.e., Inbred 10 and Sweet 100 cherry tomatoes). Samples were tested before and after enzyme treatment in uniaxial tension to determine their rate of creep, plastic and instantaneous elastic strains, breaking stress (strength), and work of fracture. The fruit peels of both cultivars exhibited pronounced viscoelastic and strain-hardening behavior, but differed significantly in their rheological behavior and magnitudes of material properties, e.g., Inbred 10 peels crept less rapidly and accumulated more plastic strains (but less rapidly), were stiffer and stronger, and had a larger work of fracture than Sweet 100 peels. The cuticular membrane (CM) also differed; e.g., Sweet 100 CM strain-softened at forces that caused Inbred 10 to strain-harden. The mechanical behavior of peels and their CM correlated with anatomical differences. The Inbred 10 CM develops in subepidermal cell layers, whereas the Sweet 100 CM is poorly developed below the epidermis. Based on these and other observations, we posit that strain-hardening involves the realignment of CM fibrillar elements and that this phenomenon is less pronounced for Sweet 100 because fewer cell walls contribute to its CM compared to Inbred 10.
我们报告了两个番茄品种（即自交系 10 和甜 100 樱桃番茄）果实果皮的生物力学和解剖结构（酶处理前后）。在单轴拉伸下测试样品，以确定其蠕变率、塑性和瞬时弹性应变、断裂应力（强度）和断裂功。两种品种的果皮都表现出明显的粘弹性和应变硬化行为，但流变行为和力学性能的幅度有很大差异，例如，自交系 10 果皮的蠕变速率较低，塑性应变积累较慢，但硬度较高，强度较大，断裂功较大，而甜 100 果皮则相反。表皮下细胞层发育的自交系 10 CM 表现出应变硬化，而表皮下 CM 发育不良的甜 100 CM 则表现出应变软化。果皮及其 CM 的力学行为与解剖学差异相关。基于这些和其他观察结果，我们假设应变硬化涉及 CM 纤维状元素的重新排列，而对于甜 100 来说，这种现象不太明显，因为与自交系 10 相比，较少的细胞壁对其 CM 有贡献。
