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IUPAC name
Abbreviations PBZ
ChemSpider 66322
Jmol-3D images Image
PubChem 73671
Molar mass 293.79 g·mol−1
Appearance off-white to beige solid
Density 1.19 g/cm3
Melting point 165-166℃
Boiling point 460.9 °C (861.6 °F; 734.0 K) at 760 mHg
26 mg/L (20 °C)
Main hazards Xn
Flash point 232.6 °C (450.7 °F; 505.8 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Paclobutrazol (PBZ) is a plant growth retardant and triazole fungicide. It is a known antagonist of the plant hormone gibberellin. It acts by inhibiting gibberellin biosynthesis, reducing internodial growth to give stouter stems, increasing root growth, causing early fruitset and increasing seedset in plants such as tomato[1] and pepper.[2] PBZ has also been shown to reduce frost sensitivity in plants.

PBZ is used by arborists to reduce shoot growth and has been shown to have additional positive effects on trees and shrubs. Among those are improved resistance to drought stress, darker green leaves, higher resistance against fungi and bacteria, and enhanced development of roots.[3][4][5][6] Cambial growth, as well as shoot growth, has been shown to be reduced in some tree species.[7]

Application methods[edit]

PBZ is normally applied to the soil to be taken up by the roots and transported via the xylem to the upper parts of the plant. Foliar application is mostly ineffective.[2] Seeds can be soaked with PBZ to reduce seedling growth.[8]


  1. ^ Berova, Malgorzata; Zlatev, Zlatko (2000). Plant Growth Regulation (PDF) 30 (2): 117. doi:10.1023/A:1006300326975  Missing or empty |title= (help)
  2. ^ a b Grossi et al. (2005). "Effects of paclobutrazol on growth and fruiting characteristics of Pitanga ornamental pepper". Acta Horticulturae 683: 333–336. 
  3. ^ Chaney et al. 1996[vague]
  4. ^ Fletcher et al. 2000[vague]
  5. ^ Rademacher 2000[vague]
  6. ^ Chaney 2003[vague]
  7. ^ Bai et al. 2004[vague]
  8. ^ Pasian and Bennett, Paclobutrazol-Soaked Ornamental Kale Seeds Produce Short Seedlings

External Links[edit]