Bhawna Bhardwaj,subject matter expert at edumarz
Solution- Hydrotropism is the movement of plant parts in response to stimulus water. Movement of the plant part can be towards or away from the water, if the plant part moves towards the water, then it shows positive hydrotropism. If the plant part moves away from the water, then it shows negative hydrotropism.
Roots show positive hydrotropism, which means that roots move towards the source of water. Normally roots grow downwards, but to get water, roots can grow sideways or even upward.Roots move towards the source of water, therefore roots show positive hydrotropism.
Experiment to demonstrate the hydrotropism:-
We take two glass troughs A and B, filled them with soil. We plant tiny seedlings in both A and B troughs. but in trough B we also put a small clay pot inside the soil. water the soil in though A daily. Do not water the soil in through B but some water in the clay is buried in the soil. Leave both the trough for a few days.
Now, dig up the seedlings from both the troughs without damaging their roots. We will find that roots of seedlings in trough A aree straight .On the other, roots of seedlings in trough B to be bent to the right side, the side where the clay pot containing water is placed.
though A, seedlings get water from both sides. In trough B, roots get water that is oozing out from the clay pot .So the roots of trough B bends towards the right where the source of water is placed. This experiment shows that roots are positive hydrotropism.
