Comprehensive Guide:
Gibberellic Acid (GA₃) Use for Capsicum Seeds
This document provides a detailed, research-based guide for the use of gibberellic acid (GA₃) in improving germination of pepper (Capsicum) seeds, particularly for wild species with dormancy issues. It also explains how GA₃ can be applied to seeds that are already in a seed starter tray or soil if they show delayed germination.
1. Purpose of GA₃ in Pepper Seed Germination
GA₃ is a plant hormone that breaks seed dormancy and speeds up germination. It is especially useful for:
– Wild species (C. chacoense, C. lanceolatum, C. cardenasii, etc.) with physiological dormancy.
– Old seeds with reduced viability.
– Species with thick seed coats that inhibit water uptake.
2. Optimal GA₃ Concentrations and Exposure Times
| Species Group | Example Accessions | GA₃ Concentration (ppm) | Soak Duration (hours) |
| Domesticated (C. annuum, C. chinense, C. baccatum, C. frutescens) | Bell peppers, Jalapeño, Habanero | 100–400 | 24 |
| Wild – C. chacoense | Carioca, Ulupica, CAP 1445 | 500–1000 | 12–24 |
| Wild – C. eximium | Ulupica Large, CAP 499 | 500 | 12–18 |
| Wild – C. lanceolatum | Guatemalan wild pepper | 1000 | 24 |
| Wild – C. cardenasii | Ulupica-like peppers | 1000 | 24 |
| Wild – C. praetermissum | Goat Pepper, CAP 1144 | 250–500 | 12 |
| Wild – C. rhomboideum | Rare wild accessions | 1000 | 24 |
| Old domesticated seeds | Aged C. chinense, C. annuum | 250–500 | 8–12 |
3. Preparing GA₃ Solutions
To prepare a GA₃ solution from 90% pure powder:
– 500 ppm: Dissolve 0.55 g GA₃ in a few drops of ethanol or warm water, then add distilled water to 1 liter.
– 1000 ppm: Use 1.1 g per liter.
– Always prepare fresh solution just before use.
4. Applying GA₃ to Seeds Already in Trays or Soil
If seeds are lagging in a starter tray:
1. Prepare a GA₃ solution (100–400 ppm for domesticated, 500–1000 ppm for wild).
2. Use a fine spray bottle or dropper to moisten the seed surface directly with the solution.
3. Apply lightly, just enough to soak the seed area; avoid waterlogging.
4. Do this once and wait 3–5 days for response before reapplying (if necessary).
In soil: GA₃ can be watered in with a dilute solution (same ppm). Apply sparingly near the seed zone. Overuse can lead to weak seedlings or fungal issues.
5. Key Considerations and Warnings
– Do not exceed 1000 ppm or 24-hour exposure.
– Overexposure causes abnormal elongation and weak seedlings.
– Maintain warm temperatures (28–30°C) for wild species germination.
– Combine with scarification or light sanding for extremely hard-coated seeds.
– Rinse seeds soaked in GA₃ before sowing to prevent mold growth.