Which one of the following growth regulators is known as "stress hormone" ?
(a) abscisic acid
(d) lndole acetic acid
Abscisic Acid (ABA) is also known as "stress hormone" or dormin, because it is produced in much higher amounts, when plants are subjected to various kinds of stresses. It often gives plant organs a signal that they are undergoing physiological stresses such as lack of water, saline soil, cold temperature and frost. ABA often cause responses that help plants and protect against these stresses.