Which one among the following hormones inhibits the growth activity in plants?

The correct answer is  Abscisic acid.

Key PointsAbscisic Acid (ABA)

• Abscisic acid (ABA) is a plant hormone that plays a crucial role in inhibiting growth and promoting dormancy in plants.
• It is known as a stress hormone because it helps plants respond to environmental stresses such as drought, salt, and cold.
• ABA induces the closure of stomata to prevent water loss during drought conditions, thereby helping the plant conserve water.
• It also promotes the abscission (shedding) of leaves, fruits, and flowers, which is a survival mechanism during adverse conditions.
• During seed development, ABA is involved in inducing and maintaining seed dormancy, ensuring that seeds only germinate under favorable conditions.
• ABA functions antagonistically to other plant hormones like auxins, gibberellins, and cytokinins, which promote growth and development.
• By inhibiting cell division and elongation, ABA helps to regulate the overall growth rate of the plant.

Additional Information

• Auxins: These are a group of plant hormones that primarily promote cell elongation, root initiation, and growth. They are crucial for various growth processes including phototropism (growth towards light) and gravitropism (growth in response to gravity).
• Cytokinins: These hormones promote cell division and shoot formation. They work in conjunction with auxins to stimulate growth and influence the differentiation of plant cells.
• Gibberellins: These are another group of plant hormones that promote stem elongation, seed germination, and flowering. Gibberellins break seed dormancy and help in the mobilization of nutrients during seed germination.
• Importance of Hormonal Balance: The growth and development of plants are regulated by a balance between growth-promoting hormones (auxins, cytokinins, gibberellins) and growth-inhibiting hormones (abscisic acid). This balance ensures that plants can adapt to varying environmental conditions and developmental stages.
• Applications in Agriculture: Understanding the role of ABA and other plant hormones is crucial for agricultural practices. For instance, ABA can be used to enhance drought resistance in crops, while auxins and gibberellins are often used to promote growth and increase yield.