What Is Naphthaleneacetic Acid and How Does It Control Plant Growth?
Technical Introduction
Naphthaleneacetic acid (C₁₂H₁₀O₂, CAS No. 86-87-3) is a synthetic auxin, a type of plant growth regulator (PGR) that mimics the activity of natural indole-3-acetic acid (IAA).
It is a white to light brown crystalline powder, sparingly soluble in water but soluble in organic solvents such as ethanol and acetone.
NAA works by stimulating or inhibiting cell elongation, division, and differentiation depending on concentration and application method.
Commercial formulations often include sodium or potassium salts of NAA to improve solubility and ease of application.
Applications
1. Agriculture
Rooting Agent: Stimulates adventitious root formation in cuttings and transplanted seedlings.
Fruit Thinning: Regulates fruit load in apples, pears, and citrus to improve fruit size and quality.
Prevention of Premature Fruit Drop: Reduces losses during harvest.
2. Horticulture
Used in ornamental plant propagation for faster and more uniform rooting.
3. Tissue Culture
Promotes callus formation and root induction in in vitro plant propagation.
Advantages
Targeted Action: Works at specific concentrations for precise growth control.
Versatile: Can be applied via foliar spray, soil drench, or dipping solutions.
Stable: Has a longer shelf life than natural auxins.
Typical Parameters
| Property | Value |
|---|---|
| Molecular Formula | C₁₂H₁₀O₂ |
| Molecular Weight | 186.21 g/mol |
| Appearance | White to light brown crystalline powder |
| Purity (%) | ≥98.0 (technical grade) |
| Solubility | Slightly soluble in water; soluble in alcohols and ketones |
| Storage | Store in a cool, dry, and well-ventilated area |
| Shelf Life | 24–36 months |
FAQs
Q1: Is NAA safe for edible crops?
A1: Yes, when used at recommended concentrations; always follow regulatory guidelines for residue limits.
Q2: Can NAA be mixed with other agrochemicals?
A2: Often compatible, but jar tests are recommended before mixing.
Q3: Does NAA work better than natural auxins?
A3: NAA is more stable and predictable than natural IAA, especially under field conditions.
Q4: Is NAA affected by sunlight?
A4: Prolonged exposure to strong UV can degrade NAA; best applied in early morning or late afternoon.
Q5: How quickly does it take effect?
A5: Rooting and fruit drop prevention effects can be observed within several days to a few weeks.
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