Multiple choice An efficient root-inducing chemical useful in horticulture is GAA IBA NAA 2, 4 – D Reveal answer Fill a bubble to check yourself B Correct answer Explanation Indole Butyric Acid (IBA) is applied to cut end of the stem to stimulate rate of formation and increase the number of roots. It is useful in horticulture as promotion of rooting would reduce death rate in nursery plants.