A precision apparatus for applying axial force on a growing root

At high soil density levels, mechanical impedance is the most important factor affecting root growth. There are two methods to investigate the effect of mechanical impedance on root growth, a direct method of applying force directly to the root and an indirect method of applying force to the medium (soil). The direct method of measuring root growth force is often preferred because it is simple and easy to control. To use the direct method, one must have a precision instrument to apply the force accurately to the root. In this paper, we report the problems experienced when we used an existing instrument and propose the design of a new instrument which is simpler but more accurate