Design an experiment to demonstrate hydrotropism.

Explanation

The type of movement of the growing plant organ, which is induced by stimulus of water is called hydrotropism.
To demonstrate hydrotropism.
Apparatus-Materials : clay, two plants, two glass
Precedure :
Take two glass troughs each filled to about `1//3` with clay. Label the trough as (A) and (B). Plant two, almost equal sized cuttings, one in each of the troughs. Add water in trough (A) and keep the clay of trough (B) dry. However in trough (B) place a small clay pot (or a cup of clay) filled with water quite close to the cutting. (See the figure) Add daily a small quantity of water in trough (A) but not in trough (B). Dig out the clay carefully in both the troughs after about a week or more.

Observation : It will be seen that the cutting in trough (A) shows a simple and straight growth of the root, while that in trough (B) shows the root curved in the direction of clay pot filled with water.
Conclusion : It can be concluded that the root grows and elongates in the direction of source of water. It means that the root shows positive hydrotropism.