Use of Oxygen Microelectrodes to Measure Aeration in the Roots of Intact Tree Seedlings

Abstract

Oxygen microelectrodes have not been widely used in studying root aeration in plants despite their potential for providing unique information on internal aeration of intact roots. Fiscus and Kramer (1970) and Vartapetian (1973) were among the first to place a small platinum electrode inside an intact root segment to measure internal oxygen partial pressure. Fiscus and Kramer (1970) used a 254 µm diameter platinum wire to measure radial movement of oxygen in excised roots of corn and jackbean. Vartapetian (1973) used a small electrode (diameter not specified) inside and outside of the roots on 50-day-old pumpkin plants to show that oxygen did not readily diffuse from the atmosphere to the roots of these plants via the stem. Bowling (1973) was probably the first to use a true microelectrode in measuring oxygen partial pressure in intact sections of plant roots. He mounted excised roots of sunflower (about 1 cm long and 400–500 µm diameter) between two cover slips and viewed at 640 x magnification. A 1 µm diameter oxygen micro-electrode was pushed through the cells by a micromanipulator to measure oxygen partial pressure at specific locations in the root.