A detailed guide on establishing and managing 5-leaf-whorl polybag rubber nurseries in Vietnam, including nursery design, seedling care, fertilization, and transplant preparation for optimal plantation success.
1. Planting Season, Site Selection, and Nursery Design
Table of Contents
The timing for planting polybag rubber seedlings depends on each region’s planting schedule. Budded stumps are planted into polybags 8–9 months before field transplanting.
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Site requirements: Select areas with suitable climate, available irrigation, and convenient transportation.
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The nursery must be designed to ensure good drainage, erosion control, and ease of management and logistics.
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Divide the nursery into 20 m × 10 m plots, with 3 m-wide paths between plots. For large nurseries, include a 5 m-wide main road for vehicle access.
Row layout options:
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Double rows: Place two parallel rows of polybags per furrow, keeping a small gap between bags (unfilled with soil). The spacing between double-row centers is 1.2 m.
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Single rows: One row per furrow, spaced 0.7–0.8 m between centers.
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Polybags are set in furrows two-thirds of their height deep.
2. Polybag and Budded Stump Specifications
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Polybags: Use virgin PE bags (0.08 mm thick), with drainage holes (5 mm in diameter, spaced 6 cm apart) over the lower half of the bag.
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Sizes:
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20 cm × 40 cm for stumps ≤ 10 months old.
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25 cm × 50 cm for stumps > 10 months old.
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Budded stumps (tum):
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Healthy, stable grafts with a single straight taproot.
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For stumps ≤ 10 months: stem diameter ≥ 12 mm (10 cm above root collar) and length 30–35 cm from the collar.
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For stumps > 10 months: diameter ≤ 24 mm, length 40–45 cm.
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Root preparation: Cut the taproot tip (“mouse tail”), seal the cut with vaseline, and apply rooting compoundbefore planting.
3. Soil Preparation and Planting
Soil Preparation
Follow the same process as in the 2–3 leaf-whorl polybag nursery:
Use loamy, well-structured soil mixed with 10 g fused phosphate + 10 g bio-organic fertilizer (or 50–100 g well-decomposed manure) per bag. Fill polybags to 2/3 height, compact gently, then top up to 1 cm below the rim.
Planting the Budded Stumps
Water polybags thoroughly one day before planting. Use a pointed stick to make a hole matching root length.
Insert the stump vertically, ensuring the graft union sits 1 cm above the soil and faces outward.
Water daily until the first leaf whorl appears, then adjust irrigation to local conditions.
4. Nursery Maintenance and Care
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Watering and Weeding: Follow the same procedure as the 2–3 leaf-whorl nursery. Keep polybags and paths free from weeds.
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Shading: Use temporary shade nets in hot regions; transparent PE covers in cold areas. Remove once plants stabilize.
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Pruning: Regularly remove rootstock shoots and lateral branches to promote healthy bud growth.
5. Fertilization Schedule for 5-Leaf-Whorl Polybag Nursery
Apply fertilizer according to Table 4 guidelines.
a) For 20 cm × 40 cm Polybags
| Application | N (g/tree) | P₂O₅ (g/tree) | K₂O (g/tree) | Equivalent NPK 16-16-8 (g/tree) |
|---|---|---|---|---|
| First | 1.0 | 1.0 | 0.5 | 6.2 |
| Subsequent | 2.0 | 2.0 | 1.0 | 12.4 |
Alternate formula (DAP + urea + K₂SO₄):
| Application | Urea (g) | DAP (g) | K₂SO₄ (g) |
|---|---|---|---|
| First | 1.4 | 2.1 | 1.0 |
| Subsequent | 2.8 | 4.2 | 2.0 |
b) For 25 cm × 50 cm Polybags
| Application | N (g/tree) | P₂O₅ (g/tree) | K₂O (g/tree) | Equivalent NPK 16-16-8 (g/tree) |
|---|---|---|---|---|
| First | 1.4 | 1.4 | 0.7 | 8.7 |
| Subsequent | 2.8 | 2.8 | 1.4 | 17.4 |
Alternate formula (DAP + urea + K₂SO₄):
| Application | Urea (g) | DAP (g) | K₂SO₄ (g) |
|---|---|---|---|
| First | 2.0 | 3.0 | 1.4 |
| Subsequent | 4.0 | 6.0 | 2.8 |
Application technique:
Mix fertilizers evenly. Drill a 3 cm-deep hole near the bag wall, place fertilizer in the hole (avoid the stem), and water immediately after application.
Foliar feeding: Apply foliar fertilizers or pesticides when needed; compatible products may be mixed safely.
6. Bag Spacing and Rearrangement
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Once seedlings reach two stable leaf whorls, space out polybags for the first time — switching to single-row layout.
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Second rearrangement occurs when plants have four stable leaf whorls.
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Conduct the final rearrangement 1–2 months before transplanting, grouping seedlings by uniform growth stage.
7. Preparing Polybags for Field Transplanting
Select polybags with:
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Stable top leaf whorl and height above 1.5 m.
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Moist soil and intact bags during transport to prevent root disturbance or bag rupture.
Keep polybags adequately moist during handling and transportation.
Conclusion
The production of 5-leaf-whorl polybag rubber seedlings is a longer, more advanced stage of nursery management, demanding precision in spacing, fertilization, and pruning to achieve strong, field-ready planting stock.
Following standardized practices for site design, nutrition, and care ensures high-quality, disease-free, and vigorous seedlings, ready to boost Vietnam’s sustainable rubber production and replanting efforts.