(i) Hydrotropisna: The growth movements in response to stimulus of water are known as hydrotropism. The roots are positively hydrotropic. It means that to get water roots move away from gravitational pull.
(ii) Hydrotropism can be demonstrated by following simple experiment: Two glass troughs A and B are filled with soil. For this purpose large size troughs are taken. In first through a small seedling is planted. A similar, equally healthy seedling is planted in second trough also. But in this trough, before planting the seedling, a small clay pot is also placed beneath the soil surface. This pot is filled with water.
Demonstration of Hydrotropism:
(a) The plant of first trough is watered daily. But no water is given to plant of second trough.
(b) Such set-up is left as such for few days.
After a few days when we dig up two seedlings carefully, we notice that the roots of the plant A are straight. The root of second plant is found bent towards the pot of water.
This experiment clearly demonstrates that the roots are positively hydrotropic. This also proves that hydrotropism is stronger than geotropism.
