Description of phototropism

Question

Give a brief description of phototropism?

Answer 1

Phototropism is movement of the plant structures in response to light. Phototropism might be negative or positive. Positive phototropism is that in which plant movement (or growth) is towards the light source and negative phototropism is that in which movement (or growth) is inverse, away from light source.

Phototropism relates to auxins because the exposition of one side of plant to light creates these hormones concentrate in darker side. This fact creates the auxin action on the stem to be positive, that is, the growth of the darker side is more intense and plant arcs towards the lighter side. In the root (when submitted to the light, in general experimentally) the auxin action is negative (over positive range), growth of the darker side is inhibited and root curves towards this side.