Department of Botany, University of Massachusetts, Amherst, Massachusetts 01002.
Plant Physiol. 1967 Nov;42(11):1545-52. doi: 10.1104/pp.42.11.1545.
Etiolated mung bean hypocotyl segments were incubated in 0.25 m mannitol solutions with indoleacetic acid. They were then deformed mechanically with a longitudinal tensile force at a constant strain rate. The magnitudes of the mechanical forces were comparable to those of the hydrostatic forces existing in normally growing tissues. Each segment was repeatedly deformed and returned to zero force. The total deformation was increased at each cycle.The irreversible and elastic changes in length and diameter were measured for each deformation and the changes in surface area and volume calculated. In addition the applied stress and the work of irreversible and of elastic deformation were determined as functions of deformation.It was found that irreversible elongation, irreversible change in surface area and total change in surface area all were linear functions of total imposed elongation. However, very little change in volume occurred during the deformations.The work of irreversible deformation was found to be independent of temperature between 8 degrees and 25 degrees . It was also virtually independent of rate of deformation measured over a 5-fold range of deformation rates.From these results it is concluded that the irreversible deformation of mung bean hypocotyl tissue occurs by plastic deformation rather than by viscous flow. Thus, the irreversible deformation occurred as a result of breaking cross-links of a cross-linked polymer system.
将黄化绿豆下胚轴片段置于含有吲哚乙酸的 0.25 m 甘露醇溶液中孵育。然后，以恒定应变速率用纵向拉伸力对其进行机械变形。机械力的大小与正常生长组织中存在的静水压力相当。每个片段都被反复变形并恢复到零力。每个循环都会增加总变形量。测量每个变形的长度和直径的不可逆和弹性变化，并计算表面积和体积的变化。此外，还确定了作为变形函数的施加应力和不可逆变形和弹性变形的功。结果发现，不可逆伸长、不可逆表面积变化和总表面积变化都是总施加伸长的线性函数。然而，在变形过程中体积变化很小。发现不可逆变形功与 8 度至 25 度之间的温度无关。它也几乎与变形速率无关，在变形速率的 5 倍范围内进行测量。根据这些结果，可以得出结论，绿豆下胚轴组织的不可逆变形是通过塑性变形而不是粘性流动发生的。因此，不可逆变形是交联聚合物体系的交联断裂的结果。
