Auxins: Indole-3-Acetic Acid (IAA) and Indole-3-Butyric Acid (IBA) in Plant Growth

Auxins are one of the primary classes of phytohormones responsible for regulating plant growth and development. The most important naturally occurring auxin is indole-3-acetic acid (IAA), while indole-3-butyric acid (IBA) is commonly used in agricultural and horticultural applications.

Auxins play a central role in:
‣ Cell elongation
‣ Root initiation
‣ Apical dominance
‣ Tropic responses (light and gravity)
IAA is the principal endogenous auxin and is involved in nearly all stages of plant development. IBA, although structurally similar, is more stable and widely used in formulations to promote root development.
Literature consistently shows that auxin concentration and distribution gradients determine plant growth patterns, particularly in root and shoot differentiation.

IAA is relatively unstable and can degrade under light, heat, and oxidative conditions. IBA is more stable, which is why it is often used in commercial products.
Both compounds are typically present at trace levels, requiring sensitive analytical techniques.

Quantifying IAA and IBA is important for:
‣ Verifying product composition
‣ Supporting formulation of rooting agents
‣ Understanding plant growth responses
‣ Ensuring consistency in biostimulant products