and germinated on damp gauze. Orderly germinating seedlings
were chosen for experiments. Pieces of metal filaments were cut approximately 3 cm in
length. One end of the metal filament was tied to a germinating seed and the other was inserted into a foamed plastic mass, which floated on the water surface. The germinating seminal roots and part of the seed were soaked in the water. The foamed plastic mass was a little smaller than the glass tank, so it could float freely on the water surface, and the growth status of rice could be easily observed because it was close to the side of the glass tank The foamed plastic
mass could be easily taken out of the water for some treatments on the rice roots, such as turning
rice seeds, divesting root cap or cutting part of root tip. The response of gravitropism could be
studied by turning the seeds horizontally.