根的生长若受到限制,土壤中即使含有充足的养分和水分,也难以发挥作用。限制根生长的因素通常是土壤机械应力。许多研究者在控制条件下对机械应力对根生长的效应都作过估计。Pfeffer把根用一块不能移动的石膏块固定后,再浇铸一块可动的石膏块将暴露的根尖包裹起来,通过可动石膏块对根的生长施加阻力,然而,对根系所受应力的测量不可能做到精确无误,而且根的生长环境也是非自然状态。Gill和Miller将麦苗种植在50μm玻璃球培养盘里通过一个橡皮隔膜对坚硬的培养盘 If the growth of the root is limited, the soil will hardly function even if it contains sufficient nutrients and moisture. The factor that limits root growth is usually soil mechanical stress. Many researchers estimate the effect of mechanical stress on root growth under controlled conditions. After the root is fixed with a piece of immobile gypsum, Pfeffer then casts a movable gypsum block to enclose the exposed apical root and exert resistance to the growth of the root through the movable gypsum block. However, the stress on the root system is measured Impossible to be accurate, but also the root growth environment is unnatural. Gill and Miller planted wheat germ in a 50 μm glass ball culture plate through a rubber diaphragm on a hard plate