Question

What will happen if the root tip is injured

Answer 1

if the root tip is injured then the plants root will not able to penetrate the soil at the rate at which it was penetrating before.
but with the passage of time it will automatically regain its original speed.

Answer 2

If the root tip gets injured, the plant will not be able to grow at the required rare.

EXPLANATION:

When the root tip gets injured, the root fails to penetrate the soil much. This means that the plant will get lesser nutrition from the soil.  

Roots supply the plants with the required water and nutrition that plants need to grow and develop. If the root fails to penetrate the soil, the plants do not get the required nutrition and thus the plant will not grow and may soon die.