Effect over the elongation growth acceleration of root segments of Zea Mays L. due to elevated external pressure

Abstract

The effect of elevated external pressure on the acceleration of elongation growth in maize root segments was studied. The growth rate of segments increases approximately by 2–2.5 times with the increase in the external pressure of up to 0.5–1 MPa. The dependence of segments’ elongation with the external pressure magnitude is shown for 0.25–2 MPa. Pre-treatment of root segments with a mercury chloride solution, which inhibits the transmembrane water transfer in roots, virtually removes the effect of pressure, which indicates the physiological nature of growth acceleration under the impact of pressure. The acceleration of elongation growth in segments is assumed to be associated with the increase in water potential within the root apoplasm (cell walls, xylem) caused by elevated external pressure. An additional reason for the acceleration of growth can be associated to the increase of the dissolved oxygen concentration in the water of root cells and tissues under such elevated pressure. The experimental data presented in the paper qualitatively are in agreement with the results of a mathematical model of elongation growth in the literature, which accounts for the parameter of pressure within the apoplasm.