Indole-3-Acetic Acid (IAA)


The term phytoregulator is used for a chemical substance which is an integral part of plant metabolism and in small concentrations can activate or depress any developmental process in that plant.

Phytoregulators can be natural or synthetic. Higher plants generate physiological active substances termed phytohormones. These natural phytoregulators are synthesized by the plant itself and act in a location distant from the source of production. There are several phytohormone groups, the best known is the auxin group.

In plants, phytohormones control the intensity of metabolism, the production of other phytohormones, production and decomposition of pigments, displacement of certain substances into certain organs or storage in them, elongation of the cell wall, the development of flowers, and also growth and growth rate (with absence of individual hormones leading to dwarfing and inhibition of development).

Auxins occur in all plants, most importantly indole-3-acetic acid. Many plants also contain indole-3-aceticaldehyde, indole-3-butyric acid, indole-3-acetonitrile and indole metabolic derivatives such as 2-hydroxyindole-3-acetic acid and ethyl indole-3-acetate with similar cell elongation action.

The principle auxin in higher plants is Indole-3-Acetic Acid (IAA). This natural auxin is synthesized by the plant itself from the amino acity tryptophan. There are several other naturally occurring auxins in higher plants, although IAA is by far the most important.

Physiological Effects of IAA

  • In high concentrations inhibition, in small concentrations promotion of longitudinal cell growth and the related water absorption of the cells. IAA causes a fairly rapid increase in the cell wall extensibility in coleoptiles and young stems.

  • Promotion of cell division of the meristematic tissue.

  • Promotion of root formation even on tissues which do normally form roots, but inhibition of growth, excpet in smallest concentrations.

  • Promotion of callus formation and callus.

  • Inhibition of budding and growth of auxiliary buds and bud formation.

  • Influencing of leaf, flower and fruit shedding.

  • Influencing of flower formation

  • Formation of parthenocarpic fruit (seedless fruit).

  • Promotion of respiration and protein formation.

The optimal tissue auxin concentration:

  • For elongation growth is typically 10-5 to 10-6 parts per million

  • For root growth 10-10 parts per million

  • For bud growth 10-8 parts per million

  • For flower promotion 10-4 parts per million

There are other classes of synthetic auxin analogs. These compounds, such as alpha-(p-chlorophenoxy) isobutyric acid or PCIB, have little or no auxin activity but specifically inhibit the effects of auxin, i.e., anti-auxins. When applied to plants, anti-auxins may compete with IAA for specific receptors, thus inhibiting normal auxin action. This inhibition can be overcome by adding excess IAA.

Specifications Sheet















1-H-Indole-3-Acetic Acid




Slightly beige crystalline powder


163-165°C (decomposition)
Assay 98.1%
Loss on drying <0.1%
Sulphated ash <0.1%

Store in properly closed drums. Avoid exposure to light, moisture, and air. Certain urban atmospheres where high smog (ozone) levels and light tend to accelerate color formation from white to beige.

Stable indefinitely if stored properly.

Not regulated

ADR: Not regulated, IMDG: Not regulated, IATA: Not regulated

1 kg, 5 kgs and 25 kgs.

Applications Data

Rooting Powder - for easy propagation plants such as common shrubs and greenhouse plants. Typical plants rooted with this strength:

  • african violet
  • azalea
  • pink pearl
  • azalea snow
  • begonia
  • bougainvillea
  • carnation
  • chrysanthemum
  • cleus
  • euonymus
  • fuchsia
  • geranium
  • hydrangea
  • jasmine
  • mock orange
  • philodendron
  • poinsettia
  • raspberry
  • rose
  • sage
  • verbena
  • willow


  • There should be as little time as possible between the time of making cuttings, treating with rooting powder and planting.
  • Cuttings should be moistened before treatment and the excess moisture shaken off.
  • Do not wet "hairy" cuttings
  • Dip basal ends of cuttings into Rooting Powder
  • Shake of excess powder by tapping cuttings
  • Plant treated cuttings in rooting media, being careful not to rub off rooting powder when planting. Inhibition or root formation is possible by the use of too high concentration of rooting powder. It is essential for successful propatation that the proper strength rooting powder for the species involved be chosen.

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