1. Seed Selection
Quality seeds are critical for uniform growth and healthy seedlings.
Criteria for Selecting Seeds:
- Mature and fully developed: Brown or dark-colored seeds indicate maturity; immature seeds have low germination.
- Intact seed coat: Avoid seeds with cracks, holes, or mold.
- Size and weight: Heavier seeds usually have higher nutrient reserves and better germination.
- Source:
- Use seeds from healthy, disease-free, and high-resin-producing parent trees.
- Prefer local provenances adapted to your region.
Seed Storage Tips:
- Store seeds in cool, dry, ventilated conditions (15–20°C, 50–60% RH).
- For short-term storage (<3 months), keep in paper envelopes.
- For longer-term storage, consider refrigeration at 4–10°C in moisture-proof containers.
- Avoid direct sunlight or excessive moisture, which reduces viability.
2. Seed Viability Testing
Viability testing ensures high germination rates before sowing.
Methods:
- a. Float Test
- Place seeds in water for 10–15 minutes.
- Viable seeds: Sink to the bottom.
- Non-viable seeds: Float (often hollow or damaged).
- Simple but approximate method; may discard some viable seeds that float.
- b. Cut Test
- Carefully cut a small portion of the seed.
- Healthy seeds: Firm, white/yellowish endosperm.
- Non-viable seeds: Dark, hollow, or shriveled inside.
- c. Germination Test
- Place 50–100 seeds on moist filter paper or sand.
- Keep in shade with moderate humidity.
- Count germinated seeds after 2–4 weeks.
- Provides accurate viability percentage.
Recommended Action: Only sow seeds with >70% viability to ensure uniform nursery growth.
3. Seed Sterilization
Sterilization reduces fungal, bacterial, and pest contamination during germination.
Steps for Sterilization:
- a. Surface Cleaning
- Remove fruit pulp completely; wash seeds under running water.
- Optional: Soak in mild detergent or water with a few drops of bleach to remove residues.
- b. Chemical Sterilization
- Sodium hypochlorite (NaOCl) 1–2%) for 5–10 minutes.
- Hydrogen peroxide (H₂O₂ 3%) can also be used for 10–15 minutes.
- Rinse seeds thoroughly with sterile or clean water to remove chemicals.
- c. Drying Before Sowing
- Air-dry seeds in shade for 30–60 minutes to reduce excess moisture.
- Avoid direct sunlight, which can damage the seed coat.
Precautions:
- Overexposure to sterilants can kill embryos and reduce germination.
- Always work with clean tools and containers to prevent contamination.
4. Key Takeaways
- Select mature, intact seeds from healthy parent trees for high germination.
- Test viability using float, cut, or germination tests to ensure nursery success.
- Sterilize seeds carefully to prevent fungal and bacterial infections, which are common in tropical environments.
- Proper handling, storage, and sterilization improve nursery establishment, seedling survival, and uniformity, which are critical for long-term plantation success.