Am J Bot. 1997 Aug;84(8):1164.
Contact forces are important in maintaining the twining habit of viny stems. A stem twining around a supporting pole puts itself into tension and uses a helical geometry to generate normal loads that are large relative to stem mass per unit length (Silk and Hubbard, Journal of Biomechanics 24(7):599-606, 1991). An electronic pressure-sensing device has been constructed to provide continuous, in vivo measurements of the forces exerted by twining stems. The pressure-sensing element is based on a thin beam load cell that is sheared by a twining stem ascending a split pole. Preliminary results show that after morning glory stems begin to coil around a supporting pole, the twining force increases in an oscillatory fashion over 3 or 4 d, corresponding to positions at least 200 mm from the apex. The force-measuring device should reveal relationships between twining forces and developmental attributes or environmental factors.
接触力对于维持藤本植物的缠绕习性很重要。茎缠绕在支撑物上会产生张力，并利用螺旋几何形状产生相对于单位长度茎质量较大的法向载荷（Silk 和 Hubbard，《生物力学杂志》24（7）：599-606，1991）。已经构建了一种电子压力感应装置，用于提供缠绕茎施加的力的连续、体内测量。压力感应元件基于薄梁称重传感器，该称重传感器被上升的分裂杆上的缠绕茎剪切。初步结果表明，在牵牛茎开始缠绕支撑物之后，缠绕力在 3 到 4 天内呈振荡方式增加，对应于距顶端至少 200mm 的位置。测力装置应该揭示缠绕力与发育属性或环境因素之间的关系。
