Functional Properties
Forchlorfenuron (CPPU) exhibits potent cytokinin-like activity. It promotes cell division, differentiation, and expansion; enhances organ formation and protein synthesis; boosts photosynthesis; increases stress resistance; and delays senescence. For melon and fruit crops, CPPU specifically stimulates flower bud differentiation, prevents physiological fruit drop, improves fruit-setting rate, and significantly accelerates fruit enlargement.
Application Techniques
a. Promoting Fruit Set, Enlargement & Quality Improvement
- Kiwifruit: 20–25 days post-flowering, dip or spray fruits once with 5–20 mg/L solution to increase weight and size.
- Loquat: At fruit diameter of 1–1.5 cm, dip once in 10–20 mg/L solution. Repeat 30–45 days later to enhance late growth and quality.
- Grape: ~15 days post-flowering (berries 10–12 mm), dip clusters once in 5–20 mg/L solution to enlarge berries and increase Brix.
- Watermelon: Spray flower buds on/pre-flowering day with 7.5–10 mg/L to improve set, sugar, and yield.
- Melon: Apply 10–20 mg/L to pedicels/buds 2–3 days pre-/on-flowering to boost set and quality.
- Cucumber: Under stress (cold, rain, low light), apply 5–20 mg/L to pedicels/buds on/pre-flowering to enhance set.
- Luffa: Spray pistils with 10 mg/L on flowering day (cultivars e.g., ‘Qiang Feng’) to increase set rate (≤97%) and yield.
- Citrus: Apply 10–15 mg/L to fruit stalk/calyx during expansion to increase size/Vitamin C/sugar.
- Strawberry: Dip fruits 6–11 days post-flowering with 20 mg/L to enlarge berries.
- Peach: Spray young fruits 10–20 mg/L ~30 days post-flowering to increase size/quality.
- Mango: For enlargement: Foliar spray 1–3 mg/L OR spray young fruits 10–20 mg/L starting 7–10 days post-flowering (pea-sized). Max 3–4 applications, >10-day intervals. Stop use ≥1 month pre-harvest. Note: High concentrations may reduce sugar:acid ratio; optimal results often with 50 mg/L GA₃.
- Cereals/Legumes: Rice (5–10 mg/L at heading), Wheat/Barley (5–10 mg/L at booting), Soybean (1–5 mg/L during flowering) to improve yield/quality.
- Radish: Foliar spray 4 mg/L 4x at 10-day intervals during root swelling to prevent bolting.
b. Preservation
- Leafy Vegetables: Foliar spray 1–2 mg/L pre-harvest to delay yellowing and extend shelf-life.
- Litchi: Dip green/pinkish young fruit (25–30 mm) in 5–10 mg/L to delay harvest 14–21 days, enhance color, improve TSS:acid ratio, and reduce browning.
- Mango: Dip fruits in 5 mg/L for 5 min before storage at 25°C to delay ripening.
Precautions
- Dosage Sensitivity: Excessive concentrations reduce soluble solids, increase acidity, delay coloring, and postpone maturity.
- Plant Health: Limited efficacy on weak/sick plants or overloaded branches; proper fruit thinning is essential.
- Crop/Environment Variation: Effects vary significantly by species/cultivar and are influenced by temperature/humidity. Always conduct small-scale tests for new uses/crops.
- Combination Use: Synergy with gibberellic acid (GA₃) or auxins is common (e.g., Citrus with GA₃), but test mixtures under expert guidance.
- Rainfastness: Reapply if rain occurs within 12 hours of treatment.
