How does phototropism occur in plants?
Movement of shoot towards light is called phototropism. This movement is caused due to more growth of cells towards the shaded side of the shoot as compared to the side of shoot towards light. More growth of cells is due to secretion of auxin towards the shaded side. • Fill a conical flask with water. • Cover the neck of the flask with a wire mesh. • Keep two or three freshly germinated bean seeds on the wire mesh. • Take a cardboard box which is open from one side. • Keep the flask in the box in such a manner that the open side of the box faces the light coming from a window. • After two or three days, you will notice that the shoots bend towards light and roots away from light. • Now, turn the flask so that the shoots are away from light and the roots towards light. Leave it undisturbed in this condition for a few days. • The old parts of the roots and shoots change directions. • New growth in shoot is in direction of sunlight. Conclusion: Shoot shows phototropism.
