失水后干豆荚的结构与力学性能

目的研究失水后豆荚的结构与力学性能,探究豆荚扭转开裂而撒射种子的生物力学机制。方法通过组织学、显微结构材料学观察、力学性能测试和高速摄像,分析绿豆荚的分层情况以及各个细胞层细胞尺寸和方向的区别,观察豆荚弹射过程,并总结豆荚弹射的原理。结果豆荚弹射过程是从豆荚的尾部开始出现裂痕,从下往上逐渐裂开。同一个豆荚的不同两片细胞排布相反,每片豆荚分为4层,其中外层上表面和中层细胞互相正交,且在两层正交的细胞层中间有一层细胞壁破裂的细胞。在豆荚成熟失水过程中,外层纤维发生收缩,中层纤维发生拉伸。结论豆荚纤维在正交方向失水收缩,累积弹性能,产生预应力,最终通过豆荚开裂来释放。

The Structure and Mechanical Properties of Pods after Dehydration

Objective To investigate the structure and mechanical properties of pods after dehydration and the biomechanical mechanism of spreading pod seed injection due to torsion crack. Methods The layered pods, the cell size and direction at different cellular layers were analyzed by histology, microstructure observation, mechanical property test and high-speed photography. The process of pod ejection was observed, and the principle of pod ejection was summarized. Results The ejection of pods started from the crack of the bottom, and cracked gradually from the bottom to the top. The cell arrangement of two parts of the same pod was opposite. Each pod was divided into 4 layers wherein the first exterior layer and the middle layer were orthogonal to each other. There was a layer of cells between the first exterior layer and the middle layer, of which the cell wall was broken. In the process of dehydration, fibers in the outer layer shrank and fibers in the middle layer stretched. Conclusions Pod fiber will be contracted in the orthogonal direction after dehydration to accumulate elastic performance and generate pre-stress, and finally the pod is cracked to release the pre-stress.