Automatic Turgor Pressure Recording in Plant Cells

Abstract

An automatically-regulated pressure probe is described, which facilitates the direct and continuous measurement of turgor pressure and water relation parameters in plant cells. An optoelectronic sensor drives a feed back system so that the position of the oil/cell sap interface in the measur­ing capillary remains constant. The sensor is easily applied to most measurement set-ups by mounting it on a focusing screen connected to the microscope used for observation. The position of the oil/cell sap boundary is sensed by its movement along the image of the capillary on the screen and can be set to any appropriate position. The optical coupling of the regulation signal is advantageous because it leaves the experimenter free to measure the electrical or other parameters of the cell. Experiments on cells of Eremosphaera viridis have shown that the device allows much faster and more exact measurements of water rela­tion parameters, and over longer periods, than the earlier method.