Abscisic acid (ABA) – Class 11 | Chapter – 15 | Biology Short Notes Series PDF

Abscisic Acid is a growth inhibitor hormone in plants. It acts as an antagonist to gibberellic acid. It is also called stress hormone because the produc­tion of hormone is stimulated by drought, water logging and other adverse environmental conditions. Abscisic acid is known as dormin as it induces dormancy in buds, underground stems and seeds.


Abscisic Acid is naturally present in fruits and vegetables and it plays an important role in managing glucose homeostasis in humans. According to the latest U.S survey, about 92 %of the population might have a deficient intake of ABA due to their deficient intake of fruits and vegetables.

Abscisic Acid Structure

Most of the plant’s responses to these abiotic conditions are mediated by abscisic acid. ABA plays important roles in seed development, maturation, synthesis of proteins, cuticular wax accumulation, leaf senescence, osmotic regulation, seed germination, etc. It is synthesized within the stem, leaves, fruits, and seeds of the plant. It acts as an antagonist to gibberellic acid. It is used as a spraying agent on trees to regulate the dropping of fruits. Favours in development and maturation of seeds. Unlike animals, plants cannot flee from potentially harmful conditions like:

  • Drought
  • The approach of winter

Functions of Abscisic Acid

  • Acts as an inhibitor of plant growth & metabolism
  • Inhibits -seed germination
  • Stimulates- closure of stomata in the epidermis to reduce transpiration and thus prevent water loss from leaves.
  • An important role in seed development, maturation & dormancy. Seed dormancy by ABA helps to withstand desiccation &other factors unfavorable for growth
  • INDUCES-Bud dormancy in a variety of plants.
  • CONTROLS-Geotropic responses of roots and stimulates positive geotropism in roots.
  • IT is produced in roots in response to decreased soil water potential and other stresses.
  • Important in plants in response to environmental stresses, including drought, soil salinity, cold tolerance, heat stress.

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By Team Learning Mantras