Alpha-Naphthalene Acetic Acid

Overview

Chemical Name: Alpha-Naphthalene Acetic Acid (α-NAA)
Common Name: Naphthylacetic acid, NAA
Type: Synthetic plant hormone (auxin)
Use in Horticulture: Rooting hormone, fruit thinning agent, plant growth regulator

Alpha-Naphthalene Acetic Acid (α-NAA) is a synthetic plant hormone belonging to the auxin family. It is widely used in horticulture to promote root development, regulate fruit set, and prevent premature fruit drop.

Chemical Properties

• Formula: C₁₂H₁₀O₂
• Appearance: White to pale yellow crystalline solid
• Solubility: Soluble in organic solvents, slightly soluble in water
• pH: Acidic in solution

Uses in Horticulture

1. Root Growth Promotion

• Used as a rooting hormone to encourage root formation in cuttings.
• Often applied as a powder, gel, or liquid dip.

2. Fruit Thinning and Growth Regulation

• Applied to fruit trees (such as apples and pears) to thin excessive fruit, improving size and quality.
• Prevents premature fruit drop in certain crops.

3. Weed Control

• In high concentrations, α-NAA can act as a herbicide by disrupting normal growth patterns.

4. Tissue Culture and Propagation

• Used in plant tissue culture to stimulate callus formation and organogenesis.

History of Use

α-NAA has been used in agriculture since the mid-20th century. It became popular as a synthetic alternative to naturally occurring auxins like indole-3-acetic acid (IAA), offering greater stability and effectiveness in plant growth regulation.

Early applications focused on commercial fruit production, where α-NAA improved yield quality by controlling fruit set and reducing crop stress. Over time, it became a standard rooting agent in horticulture and forestry.

Availability and Legal Status in the UK

In the UK, α-NAA is available in commercial plant growth regulators and rooting powders. However, its use is regulated under The Plant Protection Products (PPP) Regulations and Health and Safety Executive (HSE) guidelines.

Certain formulations may require professional use approval, and its application must comply with environmental safety standards. Gardeners and commercial growers should check with DEFRA (Department for Environment, Food & Rural Affairs) and HSE for the latest restrictions and permitted uses.