The skin protects a fruit from environmental stresses and supports the fruit’s structure. Failure of the skin leads to fruit splitting and may compromise commercial production for fruit growers. The mechanical properties of the cuticle and skin cell walls might influence the splitting susceptibility of fleshy fruits. Thin shell theory and fracture mechanics were utilized in this study to target the potential factors contributing to splitting susceptibility. The study analyzed the structure of the cuticle and epidermis in ripening grape berries and examined the temporal dynamics of berry splitting. Cuticular waxes were partially removed, and skin cell walls were manipulated using wall stiffening and loosening solutions that altered reactions involving hydrogen peroxide. A more than twofold difference in cuticle thickness among grape cultivars did not account for their differences in splitting resistance. However, while removing predominantly epicuticular wax did not alter the berries’ splitting resistance, their surface appearance and increasing yield strength following partial wax removal support the notion that cuticular waxes contribute to berry mechanical properties. Immersing berries in H2O2-based cell wall loosening solutions increased the splitting probability and accelerated berry splitting, whereas cell wall stiffening solutions decreased the splitting probability and delayed berry splitting. These results showed that both cuticle and skin cell walls contribute to the mechanical properties of grape berries and to their splitting resistance. The results also suggest that the two current explanations for fruit splitting, the critical turgor model and the zipper model, should be viewed as complementary rather than incompatible.

中文翻译：

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角质层和皮肤细胞壁在葡萄浆果分裂中具有共同和独特的作用

表皮保护水果免受环境压力并支持水果的结构。果皮破损会导致果实分裂，并可能危及水果种植者的商业生产。角质层和皮肤细胞壁的机械性能可能会影响肉质果实的分裂敏感性。本研究利用薄壳理论和断裂力学来确定导致分裂敏感性的潜在因素。该研究分析了成熟葡萄浆果的角质层和表皮结构，并检查了浆果分裂的时间动态。表皮蜡被部分去除，并且皮肤细胞壁使用改变涉及过氧化氢的反应的壁硬化和松弛溶液进行操作。葡萄品种表皮厚度的两倍以上并不能解释它们在分裂抗性方面的差异。然而，虽然主要去除表皮蜡并不会改变浆果的抗分裂性，但它们的表面外观和部分蜡去除后增加的屈服强度支持了表皮蜡有助于浆果机械性能的观点。将浆果浸入 H2○2基于 - 的细胞壁松动解决方案增加了分裂概率并加速了浆果分裂，而细胞壁硬化解决方案降低了分裂概率并延迟了浆果分裂。这些结果表明，角质层和皮肤细胞壁都有助于葡萄浆果的机械性能及其抗分裂性。结果还表明，目前对水果分裂的两种解释，即临界膨压模型和拉链模型，应被视为互补而非不相容。