Agroforestry Chapter 8 (Part 3): Eucalyptus and Teak
Agroforestry Notes · Chapter 8 · Part 3
Chapter 8 (Part 3): Eucalyptus and Teak
Eucalyptus tereticornis: site, seed, nursery, spacing and clonal propagation. Teak: distribution, silvics, seed dormancy, stumps, dona plants and uses.
1. Eucalyptus (Eucalyptus tereticornis Sm.)
| Feature | Eucalyptus |
|---|---|
| Family | Myrtaceae |
| Names | Eucalyptus, Safeda, Nilgiri; the common Indian hybrid is called Mysore gum |
| Habit | Evergreen, up to 40 m; straight clean bole, whitish mottled bark; juvenile leaves opposite, adult alternate; axillary umbels of usually 7 flowers |
| Status | Second most widely planted species in India after teak; planted everywhere except the North-East |
| Climate | Max 22–32 °C, min 2–12 °C; rainfall up to 1500 mm; up to 1700 m |
| Soil | Grows even at pH above 10, but growth is poor beyond 8.5 |
| Flowering | Twice a year (May–June and Oct–Nov); the first sets more fertile seed |
Silvics
- Strong light demander
- Frost susceptible (thin bark, essential oil)
- Good coppicer, wind-firm
- Termite damage; poor natural regeneration (ants take seed, leaves have germination inhibitors)
Seed and nursery
- Seed from ~10-year-old trees, Feb–Mar and Oct–Nov
- About 3,67,400 seeds/kg; 60–75 seedlings per gram
- Raised beds, 20 g/m², lines 10 cm apart, 2.5 mm deep; germination 5–15 days
- Prick out into polybags at 4–8 cm height
Planting
- Pits 45 or 30 cm³; 60 cm³ with soil replacement on saline-alkali land
- Plant in July (SW monsoon) or Oct–Nov (NE monsoon)
Clonal propagation
- Plus trees cut at ~12 cm; coppice shoots taken after 45–55 days
- Cuttings 10–15 cm, Benlate 200 ppm, base in IBA 6000 ppm in talc
- Rooted in vermiculite in 5–6 weeks (mist chamber)
| Purpose | Spacing |
|---|---|
| Firewood | 1 × 1 m or 1.5 × 1.5 m |
| Pulpwood / poles | 2 × 2 m or 3 × 2 m |
| Saw log | 3 × 3 m |
| Windbreaks / shelterbelts | 1.5 × 1.5 m or 2 × 1 m |
Uses: pulp, fuel, poles, and leaf oil. On bunds it is criticised for water use and allelopathy, so it is usually grown in single rows on boundaries in agroforestry.
2. Teak (Tectona grandis L.f.)
| Feature | Teak |
|---|---|
| Family | Verbenaceae as in the course; now placed in Lamiaceae |
| Names | Teak, Sagwan |
| Habit | Large deciduous tree up to 30 m; long cylindrical bole; quadrangular, channelled branchlets; deep taproot |
| Range | 10° N–25° N: India, Myanmar, Thailand, Laos; not natural in Malaysia |
| Famous plantations | Nilambur (Kerala): first plantation 1842 under Conolly (with Chathu Menon) |
| Climate | Monsoon climate only; rainfall 700–2200 mm |
| Soil | Well-drained, well-aerated, pH 6.0–8.5; fails on waterlogged and stiff clay |
Silvics
- Strong light demander, frost tender
- Drought and wind sensitive
- Fire resistant, not browsed
- Good coppicer; Lantana hinders regeneration
Seed
- Viable seed from 5–6 years
- 125–176 seeds per 100 g; germination 60–80%
- Seeds need warmth and light; may stay dormant for years in cool shade
- About 35 kg seed gives stumps for 1 ha
Breaking seed dormancy
- Natural weathering: seed spread on platforms in the August rains.
- Artificial weathering: alternate soaking and drying, 4 days each, 3–4 times.
- Pit method: layers of seed and straw watered daily for 7 days.
- Burying near an ant hill for a year; conc. H₂SO₄ for 20 minutes; scorching in a light ground fire; soaking in cowdung slurry.
Nursery and planting
- Beds 12 × 1.2 m prepared a year ahead (raised in moist, sunken in dry areas); 2.5–3 kg seed per bed gives 1200–1500 seedlings.
- Stump: 1–2 cm collar diameter, 25 cm root, 2.5 cm stem; stump planting is the most economical method, collar flush with the ground.
- Dona plants (4–6 months, raised in leaf cups) hold moisture longer than stumps.
- Pre-sprouted stumps for very dry localities; bud grafting for clonal seed orchards.
- Uses: furniture, construction, ships and railway coaches.
Memory trick: Teak stump “25 and 2.5”: 25 cm root, 2.5 cm stem. Eucalyptus seed depth 2.5 mm.
3. Quick revision box
- Eucalyptus: Myrtaceae; 2nd most planted after teak; 3,67,400 seeds/kg; frost susceptible.
- Eucalyptus clonal: IBA 6000 ppm in talc; vermiculite; coppice shoots after 45–55 days.
- Spacing: firewood 1 × 1 m; pulp 2 × 2 or 3 × 2 m; saw log 3 × 3 m.
- Teak: Verbenaceae → Lamiaceae; 10–25° N; not native in Malaysia; Nilambur 1842 (Conolly).
- Teak dormancy: weathering, pit method, H₂SO₄ 20 min, ant hill; stump 25 cm root + 2.5 cm stem; dona plants.
4. Interactive MCQ Quiz
15 questions. Tap an option to see the answer and explanation, then go to the next question.
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