Question

Select the correct statement(s) regarding auxins.

• A. Auxins promote root growth only at extremely low concentrations and they inhibit root growth at higher concentrations.
• B. Concentration of auxins which is inhibitory to root growth causes initiation of adventitious roots from the nodes or basal regions of stem.
• C. Auxins such as NAA and IBA are used to induce rooting in stem cuttings.
• D. All of the above.

Answer 1

The correct option is D All of the above.

Auxin is present in all parts of the plants in different concentrations. The concentration of auxin in different parts of the plant determines the development of the plant into a given cell type.

Auxin when present in roots at a very low concentration, promotes root formation. If it is present in higher concentration, root formation is inhibited. High concentrations of Auxin can even be toxic to the plants.

Auxin at optimum concentration promotes root formation. If the concentration increases beyond a certain level, it inhibits the formation of root and leads to the formation of adventitious roots instead.

Auxin is used in horticulture for the propagation of plants via stem cuttings because they induce root formation at the stem base.

So, the correct answer is 'All of the above'.