Paclobutrazol

Paclobutrazol

Names
IUPAC name (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol
Identifiers
CAS Number	76738-62-0
Abbreviations	PBZ
ChemSpider	66322
Jmol 3D image	Interactive graph
PubChem	73671
InChI InChI=1S/C15H20ClN3O/c1-15(2,3)14(20)13(19-10-17-9-18-19)8-11-4-6-12(16)7-5-11/h4-7,9-10,13-14,20H,8H2,1-3H3/t13-,14+/m0/s1 Key: RMOGWMIKYWRTKW-UONOGXRCSA-N InChI=1/C15H20ClN3O/c1-15(2,3)14(20)13(19-10-17-9-18-19)8-11-4-6-12(16)7-5-11/h4-7,9-10,13-14,20H,8H2,1-3H3/t13-,14+/m0/s1 Key: RMOGWMIKYWRTKW-UONOGXRCBS
SMILES CC(C)(C)[C@@H]([C@H](CC1=CC=C(C=C1)Cl)N2C=NC=N2)O
Properties
Chemical formula	C15H20ClN3O
Molar mass	293.80 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
Solubility in water	26 mg/L (20 °C)
Hazards
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

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]

References

1. Berova, Malgorzata; Zlatev, Zlatko (2000). "Physiological response and yield of paclobutrazol treated tomato plants (Lycopersicon esculentum Mill.)" (PDF). Plant Growth Regulation 30 (2): 117. doi:10.1023/A:1006300326975.
2. 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
4. Fletcher et al. 2000
5. Rademacher 2000
6. Chaney 2003
7. Bai et al. 2004
8. Claudio C. Pasian; Mark A. Bennett (January 2004). "Paclobutrazol-Soaked Ornamental Kale Seeds Produce Short Seedlings" (PDF). Ornamental Plants Annual Reports and Research Reviews (Special Circular 193).

External Links

• Paclobutrazol in the Pesticide Properties DataBase (PPDB)