Abiscisic acid is an inhibitory hormone in plants that help a plant adapt a stress.It also play a key role in the closure of plant's stomata, bud development and seed democracy.The hormone not only allow the plant to survive during times of adversity, but also assists a plant to adapting to the changing seasons.

Hope its helpful you.

Abscisic Acid: A Detailed Explanation

Abscisic acid (ABA) is a plant hormone that plays a crucial role in regulating various physiological processes in plants. It was first discovered in the 1960s and is known for its involvement in plant growth, development, and responses to environmental stressors. ABA is synthesized mainly in the chloroplasts, roots, and other parts of the plant.

Functions of Abscisic Acid:

Abscisic acid performs several vital functions in plants, including:

1. Seed Dormancy:
ABA helps in maintaining seed dormancy, preventing germination until favorable conditions are present. It inhibits the synthesis of enzymes required for seed germination and promotes the accumulation of storage proteins and lipids in the seed.

2. Stomatal Regulation:
One of the essential roles of ABA is in regulating the opening and closing of stomata. Stomata are tiny pores on the surface of leaves and stems that control gas exchange and water loss. ABA triggers stomatal closure in response to water deficit conditions, reducing transpiration and conserving water.

3. Drought and Stress Response:
During periods of water scarcity or other environmental stresses such as high salinity or extreme temperatures, ABA levels increase significantly. It helps plants adapt to these stress conditions by closing stomata, reducing water loss, and promoting root growth to enhance water absorption.

4. Leaf Senescence:
ABA is involved in the regulation of leaf senescence, the process of aging and death of leaves. It promotes the breakdown of chlorophyll and other molecules, leading to leaf yellowing and eventual shedding.

5. Fruit Ripening:
In certain fruits, such as apples and grapes, ABA is involved in the regulation of fruit ripening. It promotes the synthesis of ethylene, a plant hormone that accelerates fruit ripening processes.

6. Abscission:
ABA also plays a role in abscission, the natural shedding of leaves, flowers, or fruits. It induces the formation of an abscission layer, a separation zone between the plant and the organ that needs to be shed.

Conclusion:
Abscisic acid is a vital plant hormone with diverse functions in regulating plant growth, development, and responses to environmental stresses. Its ability to control seed dormancy, stomatal regulation, response to drought and stress, leaf senescence, fruit ripening, and abscission makes it a key player in plant survival and adaptation. Understanding the role of ABA in plants contributes to the development of strategies for crop improvement and stress tolerance.