Fig. 1.

Schematic representation of the experimental set-up for profiling of the oxygen gradient towards an adventitious root surface under water. The plant with adventitious roots was placed at the bottom of the water tank and the target adventitious root was fixed onto the background board. The whole potted Alternanthera philoxeroides plant was submerged with air-saturated water for about 1 h. The microelectrode was fixed on a micromanipulator, and used to measure the underwater oxygen profile over a distance of approx. 1200 μm by advancing a step of 50 μm every 5 s, moving towards the root surface.