Meta Description: Learn how Paclobutrazol (PBZ) – a powerful triazole plant growth regulator – inhibits gibberellin biosynthesis to reduce lodging, boost fruit yield, and enhance stress tolerance in crops. Discover its uses, benefits, and safety tips.

What Is Paclobutrazol?

Paclobutrazol (PBZ) is a member of the triazole family of plant growth regulators. It is a synthetic compound widely used in agriculture and horticulture to control plant growth, improve crop yields, and enhance stress tolerance.

Key identifiers:

CAS No.: 76738-62-0

Chemical Formula: C₁₅H₂₀ClN₃O

Molecular Weight: 293.79

Common Synonyms: PBZ, PP333

Paclobutrazol 95% TC (Technical Concentrate) appears as a white powder. It is insoluble in water but dissolves easily in polar organic solvents such as ethanol, methanol, acetone, and dichloromethane.

How Does Paclobutrazol Work?

Paclobutrazol acts by inhibiting gibberellin (GA) biosynthesis – the plant hormones responsible for cell elongation and stem growth.

Specifically, PBZ blocks the oxidation step that converts ent-kaurene into ent-kaurenoic acid in the gibberellin synthesis pathway. This interference is mediated through the inhibition of key enzymes, including cytochrome P450 oxidase and ent-kaurene oxidase.

The result is a cascade of physiological changes:

Reduced stem elongation and plant height

Increased levels of abscisic acid (ABA) and cytokinins

Enhanced root development and branching

Improved stress tolerance

Key Benefits & Applications

1. Agriculture – Higher Yields, Better Quality

Paclobutrazol is extensively used in cereal, vegetable, and fruit crops. It helps:

Reduce plant height to prevent lodging (falling over) in crops like rice and wheat

Increase fruit number and weight per tree

Improve fruit quality – higher carbohydrates, total soluble solids (TSS), and improved TSS/TA ratios with reduced acidity

Boost yield – wheat yield increased by 13.12% with optimized applications

Commonly treated crops include mango, peach, plum, apple, avocado, grapes, rice, wheat, peanuts, and soybeans.

2. Horticulture – Compact & Beautiful Ornamentals

In ornamental plants, paclobutrazol promotes compact growth and enhances flowering. It is widely used on chrysanthemums, begonias, and container-grown ornamentals to maintain aesthetic appeal without excessive vegetative growth.

3. Stress Tolerance – Protecting Crops from Environmental Stress

Paclobutrazol protects crops from drought, chilling, and heat radiation. It reduces evapotranspiration and decreases plant moisture stress by enhancing relative water content in leaves. Studies have shown that PBZ application (at 10–14 ppm) triggers coordinated morphological and biochemical changes that help plants withstand drought conditions.

4. Fungicidal Activity

Paclobutrazol also exhibits broad-spectrum antifungal properties and acts as a systemic fungicide against several economically important fungal diseases.

Application Methods & Dosage

Paclobutrazol can be applied through soil drenching, foliar spraying, or trunk injection. Soil application provides longer absorption time and greater uptake of the active ingredient than foliar spray.

Recommended dosages for common crops:

Crop              Dosage                Method

Mango tree 15–20 g/tree (15% WP) Open annular groove

Cherry tree 4–6 g/tree (15% WP) Soil application

Orange tree 500 mg/L Spray

Wheat 200 mg/L Spray at early jointing stage

Rice 300 mg/L Spray at jointing stage

Peanut 100 mg/L Spray when crop exceeds 45 cm

General rates range from 1 to 30 ppm for drench applications and 5 to 100 ppm for sprays.

Safety & Environmental Considerations

Paclobutrazol is considered moderately hazardous to humans. Key safety points:

Soil persistence: PBZ remains in soil for a long time with a half-life of more than a year under both aerobic and anaerobic conditions. Treated fields should be plowed after harvest.

Groundwater risk: The potential to contaminate groundwater at optimum concentrations is low, but the risk of exposure to aquatic life is high.

Residue levels: When applied at optimized rates, residues remain below quantifiable levels (0.01 ppm) in soils and fruits.

Temperature adjustment: Dosage should be slightly higher in high temperatures and reduced in low temperatures.

Overdose remedy: If improper use causes damage, spray gibberellic acid + brassinolide on leaves to promote recovery.

Why Choose Paclobutrazol 95% TC?

For agricultural professionals and formulators, Paclobutrazol 95% TC offers:

High purity (≥95% minimum)

Versatile applications across multiple crop types

Proven efficacy in yield enhancement and stress protection

Long-lasting activity with a single application

Final Thoughts

Paclobutrazol is a powerful, versatile, and scientifically proven plant growth regulator that helps farmers and growers achieve healthier plants, higher yields, and better quality produce. Whether you are managing lar